Psychodopygusdavisi  , Nyssomyiawhitmani  , Psychodopyguscarrerai  , Psychodopygushirsutus  , Nyssomyiaantunesi  , Trichophoromyiaubiquitalis  , Psychodopygusgeniculatus  , Pintomyianevesi  , Trichophoromyiaauraensis  , Psychodopyguscomplexus  , Nyssomyiafraihai   and Bichromomyiaflaviscutellata  . A total of 20 records of Leishmania detection corresponded to eight sand fly species. The present dataset provides updated information on the distribution of sandflies of Rondônia, including those considered potential vectors of Leishmania, which should prove useful to guide future studies.Sandflies are insects important for the transmission cycles of the leishmaniases. Despite being studied since the 1960s in the State of Rondônia (Brazil), several gaps exist regarding our working knowledge of these insects. This study aimed to construct an up-to-date database of sandflies using complementary information from the speciesLink database and the scientific literature, as well as to elaborate integrated abundance maps. We identified 153,155 records of sandflies captured in Rondônia between 1965-2021; after exclusion, 147,258 reports  associated with 15 genera and 140 species were mapped. The most abundant species observed were Leishmania. The results of the present study can serve as the basis for future studies on sandflies conducted in the State.The present study provides an extensive dataset built from all studies reporting phlebotomine sandflies in the Brazilian State of Rondônia. Online distribution maps can aid scientists who wish to consult the updated list of sand fly species and view the distribution of these insects, as well as those considered potential vectors of  Sand flies are small dipteran insects mainly known for their role as vectors in the cycle of leishmaniasis transmission . In lighMany regions in Brazil possess unexplored knowledge about these insects and it is highly possible that significant diversity remains to be discovered. Expanding the existing body of knowledge on these insects is important considering the role that sandflies play in the transmission of pathogens . TherefoLeishmania species are responsible for human cases of CL in Rondônia: Leishmaniaamazonensis Lainson & Shaw, 1972, Leishmaniabraziliensis Vianna, 1911, Leishmaniaguyanensis Floch, 1954, Leishmanialainsoni Silveira, Ishikawa, Souza & Lainson, 1987, Leishmanialindenbergi Silveira, Ishikawa & Sousa, 2002, Leishmanianaiffi Lainson & Shaw, 1989 and Leishmaniashawi Lainson, Braga, Souza, Póvoa & Ishikawa, 1989  in northern Brazil, with approximately 15,000 cases registered between 2007 and 2020. According to the Brazilian Ministry of Health, this incidence rate results from intense zoonotic transmission associated with human occupation in transmission foci . Previouwa, 1989 . HoweverThe first studies on sandflies were conducted in Rondônia in the 1960s . While s2 and has a population of 1,815,278 inhabitants throughout its 52 municipalities; it shares borders with Bolivia and the neighbouring States of Acre, Amazonas and Mato Grosso. The local climate is tropical, with annual average temperatures varying between 19.2 and 26.6°C. The dominant vegetation is dense ombrophilous forest , yet Rondônia has experienced a decrease in vegetal cover over the last 40 years , a distributed information system that combines primary data from scientific collections. We also searched the scientific literature for all studies containing taxonomic and geographic information on sand fly species collected in Rondônia. The collected information consisted of total specimens and accompanying location coordinates in decimal format  to construct regional maps.We analysed data produced by zoological collections, such as the Phlebotomine Collection - Fiocruz/COLFLEB and Invertebrates Collection/INPA. These data are freely available on speciesLink  1-100 individuals, (ii) 101-500 individuals, (iii) 501-1000 individuals, (iv) 1001-2000 individuals and (v) > 2001 individuals. 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Monte Negro, Nova Mamoré, Porto Velho, Vale do AnariTorchitte et al. 20207267C95C-5806-5AD6-A5C5-933055CEE870https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Itapuã do Oeste, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Porto Velho, Vale do AnariSilva et al. 2021F859558D-C61C-50F1-9763-C54914D37E49https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Candeias do Jamari, Costa Marques, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do AnariTorchitte et al. 20206D51E3C3-8846-5AC4-B5AB-A63FFCFC6174https://sandfliesdb.herokuapp.com/Cacaulândia, Cacoal, Itapuã do Oeste, Ji-Paraná, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do Anari, VilhenaTorchitte et al. 20208EA4B332-5BAF-546C-B509-89BA38BD04F5https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do Anari, VilhenaTorchitte et al. 202074CAF478-6D4B-538A-83A7-8F4CC748FEB9https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Itapuã do Oeste, Ji-Paraná, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do AnariTorchitte et al. 2020EB92D4C8-B9BE-5822-A22B-290206CA8149https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Monte Negro, Porto VelhoGil et al. 2003E985DCCB-F761-5921-80E8-3414B38E258Fhttps://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Candeias do Jamari, Costa Marques, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do Anari, VilhenaTorchitte et al. 2020Zapata, Depaquit & León 20122608888B-2762-5477-8C93-BF57C09F46F9https://sandfliesdb.herokuapp.com/Porto Velho6324B87D-E329-5D4E-AB5B-119635CFE849https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Porto Velho, São Francisco do Guaporé, Vale do AnariTorchitte et al. 2020DBB7AE9E-29D6-582A-9CAA-F6A39F7BBFC7https://sandfliesdb.herokuapp.com/Ariquemes, Ji-Paraná, Porto Velho13B39858-9A0E-5C71-97E1-B95FF82DB689https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Costa Marques, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do Anari, VilhenaTorchitte et al. 2020Fraiha & Ward, 1974D2CDE555-0C1C-57F9-9D30-9829E2876CD4https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Itapuã do Oeste, Monte Negro, Nova Mamoré, Porto Velho, Vale do AnariTeles et al. 2013Fraiha, Ryan, Ward, Lainson & Shaw, 1986EA64067A-F836-5C3B-B459-61CD5D47DC5Dhttps://sandfliesdb.herokuapp.com/Itapuã do Oeste, Nova Mamoré, Porto Velho, Vale do AnariSilva et al. 2021Fraiha & Ward, 198061432812-EA3F-5EF6-AFE8-482CABD0DB27https://sandfliesdb.herokuapp.com/Cacaulândia, Costa Marques, Guajará-Mirim, Itapuã do Oeste, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do AnariSilva et al. 2021720688B6-4E6B-51C3-A814-54A608CE501Bhttps://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Guajará-Mirim, Itapuã do Oeste, Monte Negro, Nova Mamoré, Porto Velho, Vale do AnariSilva et al. 20215AC22451-E1D6-514D-AC14-9CF2A69A7D1Chttps://sandfliesdb.herokuapp.com/Porto Velho4D045A14-79EF-5AF1-980F-5157778828EDhttps://sandfliesdb.herokuapp.com/Cacaulândia, Itapuã do Oeste, Monte Negro, Nova Mamoré, Porto VelhoSilva et al. 2021C8B3E68C-ACF8-56B6-A7D3-62320CE3949Ehttps://sandfliesdb.herokuapp.com/Costa Marques, Itapuã do Oeste, Monte Negro, Porto Velho, Vale do AnariResadore et al. 2018EAB094B5-EEB1-5B7A-AC86-CCF0DBE8C12Fhttps://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do AnariTorchitte et al. 20206F078D69-865F-53A3-9300-11307A82EDEAhttps://sandfliesdb.herokuapp.com/Buritis Cacaulândia Cacoal, Campo Novo, Costa Marques, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, São Francisco do Guaporé, Vale do AnariTorchitte et al. 202007A8BD8B-3244-51CD-B966-309CA6052097https://sandfliesdb.herokuapp.com/Costa Marques, Machadinho d'Oeste, Pimenta Bueno, Porto Velho, São Francisco do GuaporéSilva et al. 2021446DBCA5-76F3-5FDB-814F-B691006C6816https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto VelhoTeles et al. 201334204F95-9DD0-507B-B4FE-8A42529227C9https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Campo Novo, Monte Negro, Porto VelhoResadore et al. 20174C72FFD0-A690-5A75-A300-B17DABE9C865https://sandfliesdb.herokuapp.com/Porto Velho60AC51DA-D065-52A1-A9ED-E4C5F03D5A11https://sandfliesdb.herokuapp.com/Cacaulândia, Costa Marques, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Porto Velho, Vale do Anari, VilhenaTorchitte et al. 2020DBC8048A-61C8-5272-AD7E-5ABE07382992https://sandfliesdb.herokuapp.com/Porto Velho592B5144-58FF-585E-B2D4-1B699AE67E7Bhttps://sandfliesdb.herokuapp.com/Guajará-Mirim, Itapuã do Oeste, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do Anari, VilhenaSilva et al. 2021DAEE1F83-FD02-5A30-83A8-1F865EB09A50https://sandfliesdb.herokuapp.com/Guajará-Mirim0BC5A18D-3D66-5DAA-932D-DBF313459C4Fhttps://sandfliesdb.herokuapp.com/Itapuã do Oeste9AE6570C-ACD5-5868-939B-062DC747F4FAhttps://sandfliesdb.herokuapp.com/Monte Negro, Porto VelhoTeles et al. 2013AB3542B8-7BC5-520C-983E-78AF31508277https://sandfliesdb.herokuapp.com/Monte Negro, Pimenta Bueno, Porto VelhoTeles et al. 2013EED8B15D-72D8-5043-B4F0-EDDE8F055FEBhttps://sandfliesdb.herokuapp.com/Itapuã do Oeste, Nova Mamoré, Porto VelhoPereira Júnior et al. 2019bF7965B06-EFCC-5398-BCC0-E096166EAF8Chttps://sandfliesdb.herokuapp.com/Porto Velho0D85BF0B-3A6A-52A7-9DEF-FFCFC2A79088https://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Costa Marques, Guajará-Mirim, Itapuã do Oeste, Ji-Paraná, Machadinho d'Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do Anari, VilhenaTeles et al. 2013A3CB4590-B5FF-5546-8D44-5B1753B3EA97https://sandfliesdb.herokuapp.com/Cacaulândia, Itapuã do Oeste, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do AnariSilva et al. 20219A314B45-3FD2-5771-B0C4-4EDFECD7A51Fhttps://sandfliesdb.herokuapp.com/Cacaulândia, Itapuã do OesteLeão et al. 2020484597B1-FBBE-5864-BC41-668D6BDBCF3Fhttps://sandfliesdb.herokuapp.com/Guajará-Mirim, Itapuã do Oeste, Porto Velho, VilhenaSilva et al. 2021517A03A5-EFE8-51E3-9A96-DD4E6103CAA5https://sandfliesdb.herokuapp.com/Cacaulândia, Porto VelhoGil et al. 2003B054D87E-50F0-5E47-8B40-77AFE4A256F2https://sandfliesdb.herokuapp.com/Itapuã do OesteResadore et al. 2018830381B2-BB67-5A4F-93FD-AF271CAEFA9Fhttps://sandfliesdb.herokuapp.com/Buritis, Cacaulândia, Cacoal, Campo Novo, Guajará-Mirim, Itapuã do Oeste, Monte Negro, Nova Mamoré, Pimenta Bueno, Porto Velho, Vale do Anari, VilhenaTeles et al. 20134C658B3A-12A0-5F00-82CF-5B31708BF04Ahttps://sandfliesdb.herokuapp.com/Itapuã do Oeste, Nova Mamoré, Porto Velho, Vale do Anari, VilhenaSilva et al. 2021Psychodopygina Galati, 1995 with 132,138 records and 68 species, followed by Lutzomyiina Abonnenc & Leger, 1976 , Sergentomyiina Galati, 2003  and Brumptomyiina Galati, 2003 (290 records - 7 species) . In all, 5,887 reports were discarded mainly due to a lack of geographic coordinates. The remaining 147,258 records were distributed into four subtribes, 15 genera and 140 sand fly species. The subtribe with the most records was Psychodopygusdavisi  , Nyssomyiawhitmani  , Psychodopyguscarrerai  , Psychodopygushirsutus  , Nyssomyiaantunesi  , Trichophoromyiaubiquitalis  , Psychodopygusgeniculatus  , Pintomyianevesi  , Trichophoromyiaauraensis  , Nyssomyiashawi  (3400), Psychodopyguscomplexus  , Nyssomyiafraihai   and Bichromomyiaflaviscutellata  . These species were most commonly distributed amongst the municipalities as follows: N.whitmani (17/17), P.davisi and N.antunesi (16/17), B.flaviscutellata, P.hirsutus and T.ubiquitalis (15/17), P.nevesi, P.carrerai (13/17), N.umbratilis and P.complexus (12/17), T.auraensis (11/17), P.ayrozai (9/17) and N.fraihai (7/17)  was recorded in one species in Itapuã do Oeste. Leishmaniabraziliensis (n = 9) was detected in five sand fly species, reported in Costa Marques, Candeias do Jamari, Itapuã do Oeste and Monte Negro. Leishmanianaiffi (n = 11) was observed in five sand fly species, reported in Cacaulândia, Itapuã do Oeste and Porto Velho.We identified 20 records of lii Fig. . LeishmaThis study demonstrates the high diversity and distribution of sandflies, which are found in abundance in the Amazon rainforest. Although Rondônia has experienced a decrease in vegetal cover over the last 40 years , the StaLeishmania vector potential. Interestingly, L.braziliensis has been reported as the most prevalent agent in human cases recently reported in Rondônia , as well as specimens identified as N.yuilliyuilli from other areas of Brazil, Peru and Colombia. Morphometric analysis revealed that specimens from Brazil and Peru differed from those obtained in Colombia, mainly in terms of the parameres, which led the authors to revalidate N.fraihai. It was also concluded that the distribution of N.fraihai is cis-Andean, while N.yuilliyuilli has been found in both Andean and Trans-Andean areas, generating speculation regarding the true distribution of these species  recorded a high abundance of this species, which is similar to two different reports in Acre State   . This sa Brazil) . While bbundance . Femalesl region , as welldetected ; howevernsis DNA , reinforPsychodopygusdavisi is the species most widely distributed throughout Rondônia and most studies have reported this species in abundance—our database shows this species as present in 16 municipalities. We identified many studies detecting Leishmania infection, with this species probably being the main vector of this protozoan in the State. Natural infection was detected by PCR from females collected in the Municipality of Monte Negro, identified through sequencing as L.braziliensis , as well as in Porto Velho , N.yuilliyuilli , Pintomyiaodax , Psathyromyiarunoides and Psathyromyiashannoni. However, further taxonomic study is required to definitively confirm this speculation.Amongst all reports of species identified in Rondônia, we expostulate that some were incorrectly classified in the State: Bichromomyiainornata, by Martins et al. (1965), is the only report of this species in the State. Distribution has been reported in Bolivia, as well as in the Brazilian States of Amazonas, Rondônia and Maranhão (B.flaviscutellata (B.flaviscutellata, further study is needed to confirm the taxonomic status of this species.The original description of Maranhão . The speutellata . While tEvandromyia sp. de Baduel has only been recorded in two studies (Evandromyiaandersoni males or Evandromyiabacula females (Micropygomyiacayennensiscayennensis in the State (Pintomyiaodax (Pintomyiafiocruzi (P.odax was first reported in the State. Psathyromyiarunoides has been cited in seven studies in Rondônia (Psathyromyiapradobarrientosi, a species very similarly to P.runoides, leading these authors to speculate that P.runoides is not distributed in Rondônia ( studies . Reports females . Althoughe State , this wahe State  containsmyiaodax  is probafiocruzi , as the Rondônia . A laterRondônia .Psathyromyiashannoni is reportedly widely distributed throughout the Americas, yet this has been refuted by evidence of misidentification (Psathyromyiabigeniculata, a species of the Shannoni series that has been identified by our group (fication . While sfication , it is lur group . Moleculur group .Psychodopyguscorossoniensis, Psychodopygusguyanensis and Psychodopygusgeniculatus. Several populations of this series collected for molecular and morphological study in Ecuador resulted in the identification of P.geniculatus, Psychodopygusluisleoni Leon, Mollinedo & Le Pont, 2009 and P.corossoniensis. Two populations were observed within P.geniculatus and one was described as a new species, Psychodopygusfrancoisleponti (P.geniculatus (Other species require further taxonomic study due to the possibility of misidentification arising from morphological discrepancies, such as members of Guyanensis series: sleponti . Althougsleponti , our groiculatus . We, theiculatus .Lutzomyialongipalpis, the main vector of Leishmaniainfantum Nicolle, 1908, has rarely been reported in Rondônia, which could be explained by some factors. Many studies have demonstrated that the sylvatic distribution of this species could be restricted in accordance with its populational structure. Moreover, many studies have shown that light traps are not considered an ideal method for capturing this species, necessitating the addition of pheromones or active search to obtain higher numbers of specimens (pecimens . NeverthThe information evaluated in our study permitted a wide-ranging review of accumulated reports on sand flies over many years, thus enabling the construction of a robust database with information on these insects in the State of Rondônia. Our study was limited by the exclusion of some records from the database due to the inaccurate reporting of coordinates, which may have affected the presently-described distributions of some species. Nevertheless, we believe that the maps produced by this study could serve as reference to guide future studies investigating sand fly species in Rondônia.


The use of 2-carboxyphenylboronic acid (5 mol %) andoxalic acid(10 mol %) with 2-butanone as a solvent for the racemization of arange of enantiomerically pure secondary and tertiary alcohols isdemonstrated. The process is postulated to proceed via reversibleBrønsted acid-catalyzed C–O bond cleavage through an achiralcarbocation intermediate. One strategyto improve efficiency is to racemize the undesired enantiomer to allowrecycling of the material. In the most effective case, a dynamic kineticresolution (DKR) involves the process of combining rapid in situ substrateracemization with a KR, potentially leading to quantitative productyields in enantiomerically pure form.2Despite tremendous advancesin enantioselective synthesis, the kinetic resolution (KR) of racemicmixtures remains a cornerstone of asymmetric synthesis in academiaand industry.2 The most widely used methods in this area relyon reversible removal of the stereogenic carbinol hydrogen atom, eitherthrough deprotonation of enolizable protons or, more commonly, throughtransition-metal promoted hydrogen-transfer through a dehydrogenation–hydrogenationmechanism via an achiral ketone intermediate -3-phenyl-3-hydroxyoxindole 1 was screened in combination with oxalic acid (10 mol %) as a cocatalyst,which is known to reversibly condense with arylboronic acids to formthe corresponding boronate ester in situ.12 Preliminary screening was performed on a small-scale and the enantiomericexcess of the crude material was assessed by analytical HPLC on achiral stationary phase. Phenylboronic acid 2 gave minimalracemization after 16 h at 40 °C in chloroform (entry 1); however,the more electron-deficient arylboronic acids 3–7 provided greater reduction in enantiomeric excess underthe same conditions (entries 2–4). The most promising catalystsidentified were pentafluorophenylboronic acid 6 and 2-carboxyphenylboronicacid 7, with the latter generating the racemate of 1 (entries 5 and 6). Control studies indicated that oxalicacid (10 mol %) alone was not capable of promoting racemization (entry7) and neither was 2-carboxyphenylboronic acid 7 (5 mol%) in isolation (entry 8), demonstrating that the combination of thearylboronic acid and oxalic acid is essential for reactivity. Theuse of Dowex 50wX8 also did not lead to racemization.10 Repeating the successful racemization on a preparativescale revealed competing decomposition of 1 through analysisof the crude 1H NMR. Possible side reactions arising fromformation of a possible carbocation intermediate include etherification,12b and Friedel–Crafts alkylation processes,13 which are both precedented under arylboronic acid catalysis. Unfortunately,the side products could not be isolated in sufficient quantities toallow for unambiguous identification. A solvent screen was thereforeconducted to find conditions that promoted clean racemization withminimal loss of material. The use of arylboronic acid 7 and oxalic acid in acetonitrile gave complete racemization of 1, but was accompanied by significant decomposition, withonly 25% of rac-1 returned (entry 9).Inspired by the work of Niggemann,14 ketone-basedsolvents capable of stabilizing a cationic intermediate were trialled.The use of cyclopentanone diminished the racemization (entry 10),while acetone gave scalemic 1 in 84:16 er and with amore promising 81% recovery by NMR (entry 11). The use of 2-butanonegave a good balance of reactivity and selectivity, providing 1 in 61:39 er and 82% recovery (entry 12). Increasing thereaction temperature to 60 °C gave complete racemization afteronly 3 h, with rac-1 recovered in 70%isolated yield (entry 13).Initial studies focused on the racemizationof -methyl substituent withinoxindole 10 was tolerated. Incorporation of an electron-donating4-MeOC6H4 substituent at the C(3) position within 11 leads to significant byproductformation under the standard conditions, likely due to the increasedstability of the intermediate carbocation. Two racemic diastereoisomericproducts were obtained, consistent with undesired C–C bondformation with the enol tautomer of the 2-butanone solvent.12c Switching the solvent to acetone allowed racemic 11 to be isolated in 42% yield, alongside 39% of the ketone obtainedfrom C–C bond formation with the enol of acetone. In contrast,incorporation of a 2-naphthyl group gave effective racemization, formingracemic 12 in 82% yield. Extension to alternative C(3)-alkyl substituted alcohols 13–15 showed a reduction in enantiomeric ratio from that of thestarting materials but slower racemization than that observed withthe C(3)-aryl-substituted oxindoles. This trend isconsistent with the expectedly enhanced cation stabilizing propertiesof the doubly benzylic carbocation compared to the C(3)-alkyl-substituted carbocation.With the optimized conditions for racemization developed,the scopeand limitations of this process were assessed by changing the stericand electronic parameters of the heterocyclic tertiary alcohol substrate2. VariatS)-1-phenylethanol 16 with 2-carboxyphenylboronicacid 7 (5 mol %) and oxalic acid (10 mol %) showed thatracemization proceeded at a lower temperature than observed for thetertiary alcohols, with reaction at 40 °C in 2-butanone givinga 75:25 mixture of rac-16 to the correspondingsymmetric ether (50:50 dr). Performing the reaction at room temperatureimproved the selectivity for the racemization, providing a 93:7 mixtureof alcohol 16 (55:45 er) to its symmetric ether (50:50dr), which allowed the alcohol to be recovered in 75% yield. Increasingthe steric bulk of the alcohol through introduction of branched alkylsubstituents disfavored ether formation but required increasing temperatureto achieve racemization likely due to diminished solvation of thecarbocation intermediate. For example, i-Pr-substitutedalcohol 17 was isolated in 71% yield and 54:46 er at40 °C, while t-Bu-substituted alcohol 18 was isolated in 85% yield and 52:48 er after 1.5 h at 60°C. Varying the electronic characteristics of the aryl substituentat the carbinol was next investigated. The introduction of electron-withdrawingaryl groups disfavored racemization, with a 4-CF3C6H4 substituent on alcohol 19 leadingto no racemization even after prolonged heating at 75 °C, whilethe 4-ClC6H4 variant 20 providedpartial racemization at 60 °C. These results mirror the findingsof Bäckvall and co-workers, where electron-deficient benzylicalcohols underwent racemization at a significantly slower rate.7 Alcohol 21 bearing a weakly electron-donating4-MeC6H4 substituent was readily racemized at40 °C, as was a 2-naphthyl variant 22. The racemizationof alcohol 23 bearing a strongly electron-donating 4-MeOC6H4 substituent proceeded even at 0 °C, withhigher temperatures leading to multiple side products. Alkynyl alcohol 24 racemized readily at 60 °C, giving a 65:35 mixtureof rac-24 (59% yield) to the correspondingsymmetric ether . Decreasing the temperatureto 40 °C inhibits the etherification pathway; however, the rateof racemization was slowed. In contrast, allylic alcohol 25 led to extensive formation of the ether side-product even at roomtemperature, forming rac-25 in only22% yield. It is noteworthy that the allylic 24 and propargylic 25 alcohols provided no rearranged products via the knownboronic acid-catalyzed transposition.15 This suggests that the mechanism is likely via Brønsted acidcatalysis instead of Lewis acid catalysis.Extension of this methodologyto the racemization of secondaryalcohol substrates was then investigated 3. The re26,containing multiple stereocenters and functional group moieties wasinvestigated. Derivatives of podophyllotoxin 26 and itsdiastereoisomer, epi-podophyllotoxin 27, have been widely investigated due to their potent activity againstcancer cells via inhibition of tubulin polymerization, and a numberof methods for their synthesis have been developed.16 Treatment of commercially available podophyllotoxin 26 to the catalytic protocol in acetonitrile at room temperatureresulted in selective epimerization at the benzylic carbinol centerto give a 60:40 mixture of podophyllotoxin 26 to epi-podophyllotoxin 27 in 81% yield with purificationallowing for partial separation -3-hydroxyoxindole 1 under the standard reaction conditionswith the addition of catalytic 2,6-di-tert-butylpyridine was also subjected to the reaction conditions in thepresence of water (2 or 10 equiv) to determine the reversibility ofthe etherification. Conversion by 1H NMR demonstrated thatthe ratio of ether 28 (50:50 dr) to alcohol 16 was equivalent regardless of the amount of water added  showedone predominant species in solution, consistent with the formationof a tetrahedral sp3-hybridized boron compound (δB = 9.6 ppm).18 Direct HRMS analysisof this solution also confirmed the molecular ion of 29 as the major compound present.10 However,under the reaction conditions, 29 may exist as part ofa dynamic equilibrium with other hydrated forms, and it is thereforedifficult to unambiguously define the active catalyst present in solution.Boronate 29, or a related hydrate, is proposed to behaveas an enhanced Brønsted acid that can protonate the enantiopurealcohol, leading to an initial ion pair such as 30. ReversibleC–O bond cleavage is achieved through ionization to generatethe corresponding carbocation intermediate 31, followedby a nonselective hydration event resulting in racemization.A possible mechanism for racemization is outlinedin 7 (5 mol%) in combination with oxalic acid (10 mol %) is an efficient catalyticsystem for the racemization of enantiomerically enriched tertiary3-hydroxy-3-substituted oxindoles and a range of secondary benzylicalcohols. The process is thought to occur by reversible Brønstedacid-catalyzed C–O bond cleavage to form an achiral carbocationintermediate.In conclusion, 2-carboxylphenylboronic acid 12) atmosphere using standard vacuumline techniques and using anhydrous solvents. Anhydrous solvents (CH2Cl2 and toluene) were obtained from an anhydroussolvent system .All other reactions were performed in standard glassware with no precautionsto exclude air or moisture. Solvents and commercial reagents wereused as supplied without further purification unless otherwise stated.Room temperature (r.t.) refers to 20–25 °C. Temperaturesof 0 °C and −78 °C were obtained using ice/waterand CO2(s)/acetone baths, respectively.Reflux conditions were obtained using a DrySyn, oil bath, or sandbath equipped with a contact thermometer. Analytical thin layer chromatographywas performed on precoated aluminum plates (Kieselgel 60 F254 silica). TLC visualization was carried out with ultraviolet light(254 nm), followed by staining with a 1% aqueous KMnO4 solution.Manual column chromatography was performed in glass columns fittedwith porosity 3 sintered discs over Kieselgel 60 silica using thesolvent system stated. Automated chromatography was performed on aBiotage Isolera Four running Biotage OS578 with a UV–vis detectorusing the method stated and cartridges filled with Kieselgel 60 silica.Melting points were recorded on an Electrothermal 9100 melting pointapparatus and are uncorrected. Optical rotations [α]D20 were measured on a PerkinElmer Model 341 polarimeter operating atthe sodium D line with a 100 mm path cell at 20 °C. HPLC analyseswere obtained using either a Shimadzu HPLC consisting of a DGU-20A5degassing unit, LC-20AT liquid chromatography pump, SIL-20AHT autosampler,CMB-20A communications bus module, SPD-M20A diode array detector anda CTO-20A column oven; or a Shimadzu HPLC consisting of a DGU-20A5Rdegassing unit, LC-20AD liquid chromatography pump, SIL-20AHT autosampler,SPD-20A UV/vis detector and a CTO-20A column oven. Separation wasachieved using DAICEL CHIRALCEL OD-H or DAICEL CHIRALPAK AD-H or AS-Hcolumns. All HPLC traces of enantiomerically enriched compounds werecompared with authentic racemic spectra. 1H, 13C, 19F nuclear magnetic resonance (NMR) spectra were acquiredon either a Bruker Avance 300 (1H 300 MHz), Bruker AvanceII 400 , or a Bruker Avance II 500  spectrometer at ambienttemperature in the deuterated solvent stated. All chemical shiftsare quoted in parts per million (ppm) and referenced to the residualsolvent peak. All coupling constants, J, are quotedin Hz. Multiplicities are indicated by s (singlet), d (doublet), t(triplet), q (quartet), and combinations thereof, and m (multiplet).The abbreviation Ar is used to denote aromatic, Ph to denote phenyl,Bn to denote benzyl, br to denote broad, and app to denote apparent.Infrared spectra (νmax) were recorded on a ShimadzuIRAffinity-1 Fourier transform IR spectrophotometer fitted with aSpecac Quest ATR accessory (diamond puck). Spectra were recorded ofeither thin films or solids, with characteristic absorption wave numbers(max) reported in cm–1. High resolution mass spectrometry(HRMS) data were acquired by electrospray ionization time-of-flight(ESI-TOF) at the University of St Andrews.Reactions involvingmoisture sensitive reagents were carried out in flame-dried glasswareunder a nitrogen , boronic acid (5 mol %), and oxalicacid (10 mol %) were added to a vial. If the reaction was performedon a small-scale, stock solutions (vide infra) of the two catalystswere used and the THF from the stock solution was removed in vacuoprior to the start of the reaction. The reactants were then dissolvedin the required solvent (0.25 M) and the mixture was heated at 60°C. The reaction was stirred for the required time and then filteredthrough a silica pad and concentrated under reduced pressure. Thealcohol was analyzed by chiral HPLC and 2O and washed sequentially with 1 M NaOH, brine, thendried with MgSO4, filtered, and concentrated in vacuo.The reaction mixture was then filtered through a silica pad and concentratedunder reduced pressure. The alcohol was analyzed by chiral HPLC and 1H NMR.The appropriate alcohol (1 equiv), boronic acid (5 mol %), and oxalicacid (10 mol %) were added to a vial. If the reaction was performedon a small-scale, stock solutions (vide infra) of the two catalystswere used and the THF from the stock solution was removed in vacuoprior to the start of the reaction. The reactants were dissolved inthe required solvent (0.25 M) and the mixture was heated to the requiredtemperature for the described time. The reaction was diluted withEtBoronic acid  and THF (1 mL) were addedto a 2 mL volumetric flask. Once the mixture was homogeneous (aftersonication) THF was added until the total volume of the mixture hadreached 2 mL.Oxalic acid  and THF (1 mL) were placed in a 2mL volumetric flask. Once the mixture was homogeneous (after sonication)THF was added until the total volume of the mixture had reached 2mL.3R)-1-benzyl-3-hydroxy-3-phenylindolin-2-one 1 , 2-carboxyphenylboronic acid 7, and oxalic acid  were reacted in 2-butanone (2.6 mL) for 3h at 60 °C. The reaction was concentrated under reduced pressureand purified by column chromatography (Petrol:EtOAc 3:1) to give rac-1-benzyl-3-hydroxy-3-phenylindolin-2-one 1 . Chiral HPLC analysis, Chiralpak AD-H  tR (R): 17.8min, tR (S): 21.6 min,51:49 (R:S) er.Following General Procedure A, (R)-3-hydroxy-1-methyl-3-phenylindolin-2-one 8 , 2-carboxyphenylboronic acid 7 , and oxalic acid were reacted in 2-butanone(1.2 mL) for 3 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:1) to give rac-3-hydroxy-1-methyl-3-phenylindolin-2-one 8 . Chiral HPLC analysis, ChiralpakAD-H  tR (R): 27.4 min, tR (S):30.7 min, 51:49 (R:S) erFollowing General Procedure A, (R)-3-hydroxy-1-allyl-3-phenylindolin-2-one 9 , 2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone(1.2 mL) for 2 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:3) to give rac-3-hydroxy-1-allyl-3-phenylindolin-2-one 9 . Chiral HPLC analysis, ChiralpakOD-H  tR (S): 14.0 min, tR (R):16.0.1 min, 52:48 (R:S) er.Following General Procedure A, (R)-1-benzyl-3-hydroxy-5-methyl-3-phenylindolin-2-one 10 , 2-carboxyphenylboronicacid 7 , andoxalic acid were reacted in 2-butanone(1.2 mL) for 4 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:5) to give rac-1-benzyl-3-hydroxy-5-methyl-3-phenylindolin-2-one 10 . Chiral HPLC analysis, ChiralpakAD-H  tR (R): 12.2 min, tR (S):15.6 min, 50:50 (R:S) er.Following General Procedure D, (R)-1-benzyl-3-hydroxy-3-(4-methoxyphenyl)indolin-2-one 11 , 2-carboxyphenylboronicacid 7 , andoxalic acid were reacted in 2-butanone(1.1 mL) for 2 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:3) to give two isomers of 1-benzyl-3-(4-methoxyphenyl)-3-(3-oxobutan-2-yl)indolin-2-one S23  as a colorless oil and S24  as a white solid. 1-Benzyl-3-(4-methoxyphenyl)-3-(3-oxobutan-2-yl)indolin-2-one S23: 1H NMR  δH 7.74 , 7.38–7.44, 7.18–7.32 , 7.10 , 6.79–6.85 , 6.75 , 4.90 , 4.00 , 3.77 , 2.02 , 0.97 ; 13C{1H} NMR  δC 209.6, 178.1, 158.9, 143.4, 136.0, 130.6,129.1, 128.9, 128.4, 128.3, 128.0, 127.7, 127.3, 122.6, 114.0, 109.4,57.6, 55.3, 53.5, 44.2, 31.1, 13.3; IR νmax (film)2931 (C–H), 2359, 1701 (C=O), 1607 (C=C), 1508,1352, 1250, 1182 cm–1; HRMS (NSI+) calculatedfor C26H25NO3Na+ [M +Na]+ requires 422.1727, found 422.1713 (−3.3 ppm).1-Benzyl-3-(4-methoxyphenyl)-3-(3-oxobutan-2-yl)indolin-2-one S24: mp 105–108 °C; 1H NMR  δH 7.33–7.40 , 7.18–7.29, 7.07 , 6.81–6.87, 6.74 , 4.94 , 4.84 , 3.86 , 3.78 , 2.06 , 1.37 ; 13C{1H} NMR  δC 208.5, 178.8, 159.1, 143.8,136.0, 130.3, 130.1, 128.7, 128.7, 128.2, 127.5, 127.2, 125.8, 122.0,114.1, 109.8, 56.6, 55.4, 54.8, 44.2, 29.0, 12.8; IR νmax (solid) 2926 (C–H), 1697 (C=O), 1607 (C=C),1508, 1354, 1253, 1180 cm–1; HRMS (NSI+) calculated for C26H25NO3Na+ [M + Na]+ requires 422.1727, found 422.1710 (−4.0ppm).Following General ProcedureA, (R)-1-benzyl-3-hydroxy-3-(4-methoxyphenyl)indolin-2-one 11 , 2-carboxyphenylboronicacid 7 , andoxalic acid were reacted in acetone(0.6 mL) for 2 h at 40 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:2) followed by flash column chromatography (CH2Cl2:EtOAc 95:5) to give rac-11 asa yellow solid , and 1-benzyl-3-(4-methoxyphenyl3-(2-oxopropyl)indolin-2-one S25 as white solid . 1-Benzyl-3-hydroxy-3-(4-methoxyphenyl)indolin-2-one 11: Chiral HPLC analysis: Chiralpak IC  tR (R): 15.6 min, tR (S): 21.0 min, 51:49 (R:S) er. 1-Benzyl-3-(4-methoxyphenyl)-3-(2-oxopropyl)indolin-2-one S25: mp 104–106 °C; 1H NMR  δH 7.20–7.35 , 7.18, 7.03 , 6.80–6.85 , 6.73 , 5.00 , 4.90 , 3.77 , 3.65,3.52 , 2.06 ; 13C{1H} NMR  δC 204.4, 178.8, 159.1, 143.9, 136.2, 131.8, 131.6, 128.8, 128.4, 127.9,127.5, 127.3, 124.0, 122.4, 114.2, 109.7, 55.4, 52.6, 51.2, 44.3,30.3; IR νmax (solid) 2912 (C–H), 1705 (C=O),1606 (C=C), 1508, 1355, 1256, 1180, 1168 cm–1; HRMS (NSI+) calculated for C25H23NO3Na+ [M + Na]+ requires 408.1576,found 408.1557 (−4.7 ppm).Following General ProcedureD, (R)-1-benzyl-3-hydroxy-3-indolin-2-one 12 , 2-carboxyphenylboronicacid 7 , andoxalic acid were reacted in 2-butanone(1.0 mL) for 2.5 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:3) to give rac-1-benzyl-3-hydroxy-3-indolin-2-one 12 . Chiral HPLC analysis: ChiralpakIA  tR (R): 24.8 min, tR (S):31.0 min, 52:48 (R:S) er.Following General Procedure A, (R)-3-allyl-1-benzyl-3-hydroxyindolin-2-one 13 , 2-carboxyphenylboronic acid 7 , and oxalic acid were reacted in 2-butanone(1.2 mL) for 5 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography to provide1-benzyl-3-ethyl-3-hydroxylindolin-2-one 13 . Chiral HPLC analysis: Chiralpak OD-H  tR (R): 32.1 min, tR (S): 38.4 min, 94:6 (R:S) er.Following General Procedure A, (R)-1-benzyl-3-ethyl-3-hydroxylindolin-2-one 14 , 2-carboxyphenylboronic acid 7 , and oxalic acid were reacted in 2-butanone(1.1 mL) for 30 h at 60 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (Petrol:EtOAc1:3) to give rac-1-benzyl-3-ethyl-3-hydroxylindolin-2-one 14 . Chiral HPLC analysis: ChiralpakIC  tR (R): 7.6 min, tR (S):12.5 min, 75:25 (R:S) er.Following General Procedure A, (R)-1-benzyl-3-hydroxy-3-isopropyl indolin-2-one 15 , 2-carboxyphenylboronic acid 7 , and oxalicacid  were reacted in2-butanone (0.85 mL) for 18 h at 60 °C. The reaction was concentratedunder reduced pressure and purified by column chromatography 1-benzyl-3-hydroxy-3-isopropylindolin-2-one 15 . Chiral HPLCanalysis: Chiralpak AD-H  tR (R): 23.6 min, tR (S): 28.5 min, 84:16 (R:S) er.Following General Procedure A, (S)-1-phenylethanol 16 ,2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone(12 mL) for 2 h at room temperature. The reaction was concentratedunder reduced pressure and purified by column chromatography (10%EtOAc:Hexane) to give rac-1-phenylethanol 16 . Chiral HPLC analysis: Chiralpak OD-H  tR (R): 8.1 min, tR (S): 9.9 min, 55:45 (S:R) er.Following General Procedure B, ,2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone(12 mL) for 4 h at 50 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (2% EtOAc:Hexane)to give )dibenzene as a colorless oil 28  as a 1:1 mixture of diastereomers.Spectroscopic data in accordance with the literature.19 )dibenzene (28) (1:1mixture of diastereomers): 1H NMR  δH 7.24–7.47 , 4.61 , 4.33 , 1.55 , 1.47 .Following a modified General Procedure D, S)-2-methyl-1-phenylpropanol 17 , 2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone (1.2 mL) for 2 h at room temperature.The reaction was concentrated under reduced pressure and purifiedby column chromatography (10% EtOAc:Hexane) to give rac-2-methyl-1-phenylpropanol 17 .Chiral HPLC analysis: Chiralpak AD-H  tR (R): 21.6 min, tR (S): 24.1 min, 55:46 (S:R) er.Following General Procedure B, (S)-2,2-dimethyl-1-phenylpropanol 18 , 2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone (1.5mL) for 1.5 h at 60 °C. The reaction was concentrated under reducedpressure and purified by column chromatography (10% EtOAc:Hexane)to give rac-2,2-dimethyl-1-phenylpropanol 18 . Chiral HPLC analysis: Chiralpak OD-H tR (S): 6.3min, tR (R): 8.9 min,52:48 (S:R) er.Following General Procedure B, (S)-2,2-dimethyl-1-(4-(trifluoromethyl))propan-1-ol 19 , 2-carboxyphenylboronic acid 7 , and oxalicacid  were reacted in 2-butanone(0.35 mL) for 2 h at 75 °C. The reaction was then diluted withether, washed with 1 M NaOH, brine, dried with MgSO4, andfiltered. The resulting (S)-2,2-dimethyl-1-(4-(trifluoromethyl)phenyl)propan-1-ol 19 was analyzed by HPLC and showed no erosion of enantioenrichment.Chiral HPLC analysis: Chiralpak OJ-H  tR (S): 9.1 min, tR (R): 10.0 min, 97:3 (S:R) er.Following General Procedure B, (S)-1-(4-chlorophenyl)-2,2-dimethylpropan-1-ol 20 , 2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone (0.75 mL)for 6 h at 60 °C. The reaction was concentrated under reducedpressure and purified by column chromatography (10% EtOAc:Hexane)to give 1-(4-chlorophenyl)-2,2-dimethylpropan-1-ol 20 . Chiral HPLC analysis: Chiralpak IC  tR (S): 7.7 min, tR (R): 7.2 min, 73:27 (S:R) er.Following General Procedure B, (S)-2,2-dimethyl-1-(p-tolyl)propan-1-ol 21 , 2-carboxyphenylboronicacid 7 , and oxalicacid  were reacted in 2-butanone (1.7 mL) for2 h at 40 °C. The reaction was concentrated under reduced pressureand purified by column chromatography (10% EtOAc:Hexane) to give rac-2,2-dimethyl-1-(p-tolyl)propan-1-ol 21 . Chiral HPLC analysis: ChiralpakOJ-H  tR (S): 6.8 min, tR (R):7.1 min, 54:46 (S:R) er.Following General Procedure B, (S)-2,2-dimethyl-1-propan-1-ol 22 , 2-carboxyphenylboronic acid 7 , and oxalicacid  were reacted in 2-butanone(0.4 mL) for 2 h at 40 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (10% EtOAc:Hexane)to give rac-2,2-dimethyl-1-propan-1-ol 22 . Chiral HPLC analysis: ChiralpakOJ-H  tR (S): 19.4 min, tR (R):24.8 min, 56:44 (S:R) er.Following General Procedure B, (S)-1-(4-methoxyphenyl)-2,2,-dimethylpropan-1-ol 23 , 2-carboxyphenylboronic acid 7 , and oxalicacid  were reacted in MeCN(0.76 mL) for 2 h at 0 °C. The reaction was concentrated underreduced pressure and purified by column chromatography (10% EtOAc:Hexane)to give rac-1-(4-methoxyphenyl)-2,2-dimethylpropan-1-ol 23 . Chiral HPLC analysis: ChiralpakAD-H  tR (R): 23.6 min, tR (S):25.7 min, 67:33 (S:R) er.Following General Procedure B, (S)-4-phenylbut-3-yn-2-ol 24 , 2-carboxyphenylboronicacid 7 , and oxalic acid were reacted in 2-butanone (3 mL) for2 h at 60 °C. The reaction was concentrated under reduced pressureand purified by column chromatography (10% EtOAc:Hexane) to give rac-4-phenylbut-3-yn-2-ol 24  and )dibenzene S26 . Spectroscopic data in accordance with the literature.20 4-Phenylbut-3-yn-2-ol 24: ChiralHPLC analysis: Chiralpak OD-H  tR (S): 28.5 min, tR (R): 11.3 min, 50:50 (S:R) er. )dibenzene S26 (1:1mix of diastereomers): 1H NMR  δH 7.41–7.51 , 7.25–7.35, 4.86 , 4.73 , 1.60 , 1.59 .Following General Procedure B, -4-phenylbut-3-en-2-ol 25 , 2-carboxyphenylboronic acid 7 , and oxalic acid  were reacted in 2-butanone (1.6 mL) for 2 h at room temperature.The reaction was concentrated under reduced pressure and purifiedby column chromatography (20% EtOAc:Hexane) to give rac-(E)-4-phenylbut-3-en-2-ol 25  and -oxybis)dibenzene S27 . Spectroscopic data in accordance withthe literature.21 (E)-4-Phenylbut-3-en-2-ol 25: Chiral HPLC analysis: Chiralpak OD-H  tR (S): 25.0 min, tR (R): 15.1 min, 50:50 (S:R) er. -Oxybis)dibenzene S27 (2.6:1 mixtureof diastereomers): 1H NMR  δH 7.20–7.45 , 6.55 , 6.52 , 6.21 , 6.14 ,4.13–4.31 , 1.37 .Following General Procedure B, , 2-carboxyphenylboronic acid 7 , and oxalic acid were reacted in 2-butanone (2 mL) for 2 h at room temperature. Thereaction was concentrated under reduced pressure and purified by columnchromatography (50% EtOAc:Hexane) to give podophyllotoxin 26  and epi-podophyllotoxin 27  and  for an overall yield of 81% 60:40 dr. Spectroscopic datain accordance with the literature.22 Podophyllotoxin 26: 1H NMR  δH 7.11 , 6.51 , 6.37, 5.98 , 4.78 , 4.57–4.66 , 4.10 , 3.81 , 3.76 , 2.69–2.89, 1.98 . epi-Podophyllotoxin 27: 1H NMR  δH 6.87 , 6.55 , 6.28 , 5.98 , 4.86 , 4.61 , 4.31–4.42, 3.80 , 3.74 , 3.27 , 2.83 , 1.82.FollowingGeneral Procedure B, podophyllotoxin


Artemisia pallens and Tagetes mendocina, has been developed. The key steps in the five-step 36% overall yield synthesis are a CpTiIIICl2 mediated Barbier-type allenylation of a linear aldehyde and the formation of a 2,5-dihydrofuran scaffold through a Ag(I)-mediated cyclization. Neither of the reported spectral data for dihydrorosefuran match those of the synthetic product, suggesting that the isolated compound from Tagetes mendocina is in fact the natural product rosiridol, while the real structure of the product from Artemisia pallens remains unknown.An original synthesis of the structure of dihydrorosefuran, a compound allegedly identified in  Artemisia pallens is an aromatic plant from southern India whose essential oil, known as Davana oil, has shown increasing interest mainly for its use in some beverages, cakes, pastries, etc., as well as in the perfumery industry  [Our synthetic strategy is based on two metal-mediated steps . In thisiIIICl2] –12.4) + calcd for C10H17O3, 185.1178; found, 185.1158. A lactone is formed as side product (0–10%) when the HCl solution used for the workup has a concentration higher than 3%. Compound 5: IR (ATR) ν (cm−1): 2982, 2927, 1960, 1772, 1427, 1331, 1162, 974, 918, 855; 1H NMR  δ 4.89 , 4.86 , 2.55 , 2.30 , 1.79  ppm; 13C{1H} NMR  δ 206.0 (C), 177.0 (C), 98.0 (C), 80.4 (CH), 77.5 (CH2), 28.5 (CH2), 26.1 (CH2), 15.0 (CH3) ppm; HRMS–ESI : [M + H]+ calcd for C8H11O2,139.0759; found, 139.0782.Under an Ar atmosphere, dry THF (8 mL) that was deoxygenated prior to use was added to a mixture of CpTiCl3  in acetone (2 mL) was added to a suspension of AgNO3  in acetone (1.5 mL) in the absence of light, and the mixture was stirred at 40 °C overnight. Brine was added and the mixture was extracted with Et2O. The organic phase was dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel flash column chromatography (n-hexane/EtOAc 9:1) to afford ethyl 3-propanoate  isolated as colorless oil. IR (ATR) ν (cm−1): 2969, 2927, 2849, 1731, 1442, 1376, 1251, 1160, 1092, 1026, 895, 734. 1H NMR  δ 5.53 , 4.69 , 4.56 , 4.15 , 2.39 , 2.12–2.06 , 1.83–1.74 , 1.72 , 1.27  ppm; 13C{1H} NMR  δ 173.9 (C), 137.2 (C), 121.3 (CH), 86.4 (CH), 74.7 (CH2), 60.3 (CH2), 29.4 (CH2), 28.9 (CH2), 14.2 (CH3), 12.3 (CH3) ppm; HRMS–ESI : [M + H]+ calcd for C10H17O3,185.1172; found, 184.1162.A solution of the allenol 2 atmosphere, methylmagnesium bromide  was diluted with dry Et2O (1.5 mL). A solution of ethyl 3-propanoate  in Et2O (1 mL) was added dropwise and the reaction mixture was stirred for 3 hours at room temperature. The reaction was quenched with saturated NH4Cl and extracted with EtOAc. The combined organic layer was washed with saturated NaHCO3, brine, and dried over anhydrous MgSO4. The solvent was evaporated in vacuum and the residue was purified using column chromatography (n-hexane/EtOAc 7:3) to give 2-methyl-4-butan-2-ol  isolated as colorless oil. IR (ATR) ν (cm−1): 3425, 2969, 2922, 2852, 1636, 1444, 1382, 1089, 1057, 1025; 1H NMR  δ 5.51 , 4.68 , 4.58 , 2.05 , 1.82 , 1.72 , 1.57 , 1.24  ppm; 13C{1H} NMR  δ 137.8 (C), 120.7 (CH), 87.7 (CH), 74.5 (CH2), 70.4 (C), 38.5 (CH2), 29.5 (CH3), 29.4 (CH3), 28.3 (CH2), 12.5 (CH3) ppm; HRMS–ESI : [M + H]+ calcd for C10H19O2, 171.1385; found, 171.1368.Under an N®-15  and 2-methyl-4-butan-2-ol , based on the previously reported literature procedure + calcd for C10H17O, 153.1274; found, 153.1262.The reaction of amberlystrocedure , affordeFile 1Experimental procedures, characterization of other substances, and copies of IR, NMR spectra and HPLC chromatograms.


The emergence of drug-resistant bacterial strains continues to be one of the major challenges of medicine. For this reason, the importance of searching for novel structures of antibacterial drugs chemically different from the currently known antibiotics is still of great importance. In this study, we synthesized the thiosemicarbazide and 1,3,4-thiadiazole derivatives and tested them for antibacterial activity. In in vitro tests, we examined the activity of the synthesized substances against Gram-positive and Gram-negative bacteria strains. While all 1,3,4-thiadiazoles tested lacked significant activity, the antimicrobial response of the thiosemicarbazides was moderate and it was also dependent on the type and position of the substituent on the phenyl ring. The highest activity towards all Gram-positive bacteria strains was shown by all three linear compounds containing the trifluoromethylphenyl group in the structure. The MIC (minimum inhibitory concentration) values were in the range of 3.9–250 µg/mL. Additionally, we try to explain the mechanism of the antibacterial activity of the tested compounds using the molecular docking to DNA gyrase and topoisomerase IV, following previous reports on the molecular basis of the activity of thiosemicarbazides. Docking simulations allow the purposing dual mechanism of the antibacterial activity of the synthesized compounds through inhibition of topoisomerase IV DNA gyrase with the moderate prevalence of the topoisomerase pathway. The introduction of penicillin to medical practice in 1942 started a scientific race in the development of new drugs effective in combating pathogenic bacteria. Along with the growing number of antibacterial drugs and the availability of antibiotics, the resistance of pathogens to therapeutic substances increased drastically [2-NH-C (=S) NH2 moiety in the structure of molecules [In recent years, scientists have been interested in the use of small organic molecules, including heterocyclic compounds, as promising therapeutic substances ,6,7,8,9.olecules . The 1,3olecules .The research work carried out by our team in previous years indicates the high potential of aryl thiosemicarbazides to inhibit type IIA topoisomerases (DNA gyrase and topoisomerase IV) ,27,28,29In our research, we also tried to answer questions about the mechanism of action of the newly synthesized compounds using the molecular docking technique. As the most probable strategy, based on previous works, we considered the inhibition of topoisomerases IIA.SA13-SA18, ST13-ST18) and previously obtained derivatives . In the previously published work, we presented the antitumor activity of some of the 1,3,4-thiadiazoles [The synthesis of thiosemicarbazides and their cyclic analogs with the 1,3,4-thiadiazole ring was carried out according to the synthetic route presented in diazoles  presentediazoles . The evaSA) with good yields (43–95%). The obtained compounds were cyclized in concentrated sulfuric acid to the corresponding 1,3,4-thiadiazoles (ST), which were obtained with a yield of 22–70%. The structures of the new compounds described for the first time were determined using the IR, 1H NMR, 13C NMR spectroscopy and elemental analyzes.The reaction of 3-methoxyphenylhydrazide with the appropriate aryl isothiocyanate in refluxing ethanol gave 1-(3-methoxyphenyl)-4-aryl-thiosemicarbazides . 1H NMR spectra confirmed the cyclization and the preparation of new 1,3,4-thiadiazole derivatives from the previously synthesized thiosemicarbazides. N1, N2 and N4 protons characteristic for thiosemicarbazides were not detected in 1,3,4-thiadiazole compounds. In the 1H NMR spectra of compounds ST13-ST18, the signals of the protons of the amine group between 10.34 and 10.79 ppm were visible. In two cases, we did not observe this proton. This is possible for labile protons that are bonded to the nitrogen atom. In 1H NMR spectra, the protons of the OCH3 group of all-new synthesized compounds show singlet signal at δ ~3.80–3.87 ppm. The 13C NMR spectra of the carbons of the compounds showed the carbon signals due to the resonance of the methoxy group in the range 55.75–55.84 ppm. The remaining carbon signals are appropriate for confirming the structure of the new compounds. In IR spectra of thiosemicarbazide derivatives absorption bands for C=O at 1664–1689 cm−1 were observed.1H NMR and 13C NMR spectra for all new compounds are presented in The The antibacterial activity of the synthesized thiosemicarbazides and 1,3,4-thiadiazole derivatives was tested based on the inhibition of bacterial growth in vitro using the broth microdilution method. The antibacterial results  are reported in Klebsiella pneumoniae ATCC 13883 and Escherichia coli ATCC 25922 bacteria, and oxidase-positive Pseudomonas aeruginosa ATCC 27853 bacteria. According to our screening results, some of the tested thiosemicarbazides showed potential antimicrobial activity against selected Gram-positive bacteria including the Gram-positive strains of Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 43300, Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240. The reference drugs used in our investigations were ciprofloxacin and cefuroxime. The MIC values for this antibiotics were 0.24–0.98 µg/mL and 0.24–62.5 µg/mL, respectively.All tested compounds showed a lack of antimicrobial activity against the reference strains of Gram-negative oxidase-negative ST) showed a lack or negligible antibacterial activity against both Gram-positive and Gram-negative strains, except for compounds with 4-bromophenyl substituent (ST16), which showed promising activity against S. epidermidis ATCC 12228 with MIC value of 31.25 µg/mL, and M. luteus ATCC 10240 with MIC value of 15.63 µg/mL.1,3,4-thiadiazole derivatives  and S. aureus ATCC 43300 ) was demonstrated by thiosemicarbazide SA1, with a MIC value of 62.5 µg/mL against both strains. This compound has a chlorine atom in position 2 in the phenyl ring. The introduction of a second chlorine atom into the phenyl ring (SA17) results in a loss of activity against the MRSA strain. The thiosemicarbazides SA10, SA11, SA14 with MIC values ranging from 125 µg/mL to 250 µg/mL also showed significant activity against both strains. Compounds with chlorine atom in position para in the phenyl ring (SA3 and ST3) are two times more active towards MRSA than MSSA. Against S. epidermidis ATCC 12228 the highest activity with a MIC value of 31.25 µg/mL was demonstrated by SA11, ST7, ST8, and ST16. It is the only bacterial strain that is more sensitive to cyclic compounds than their linear precursors. Compounds with various substituents  in position ortho SA1, SA7, SA10, ST4 showed antibacterial activity against S. epidermidis ATCC 12228 with a MIC value of 62.5 µg/mL. The strain most sensitive to the tested compounds turned out to be M. luteus ATCC 10240. The highest activity against these bacterial strains with a MIC value of 3.9 µg/mL was shown by the SA11 and SA12 thiosemicarbazides. The compound that showed the highest activity against all tested Gram-positive strains  was SA11, thiosemicarbazide having a 3-trifluoromethylphenyl substituent. Unfortunately, despite testing a large number of compounds, it is not possible to derive a relationship between structure and activity in the studied groups of derivatives.According to our results, the highest antibacterial activity against two bacterial M. luteus ATCC 10240 resulted mainly equivalent concentration to MIC indicating that they are bactericidal rather than bacteriostatic agents. According to presented data, the MBC of tested compounds does not usually exceed by a factor greater than one to four times higher than their respective MIC values against only M. luteus ATCC 10240 bacteria, indicating their bactericidal effect. The MBC determined against staphylococci resulted from 16 to more times higher compared to MIC, indicating their bacteriostatic effect against these Gram-positive bacteria.Minimal bactericidal concentration (MBC) was detected for compounds with MIC value ≤ 250 µg/mL. The MBC determined for the selected compounds  against SA) showed the ability to inhibit the growth of Gram-positive bacterial strains. The results are interesting for MRSA, the resistant subpopulation of a major pathogen that is associated with serious community-acquired and nosocomial diseases. This species can cause a large number of worldwide diseases and is important especially for hospital-associated infections [In conclusion, most of the tested thiosemicarbazides  did not inhibit the growth of Gram-positive and Gram-negative bacteria. These compounds were previously synthesized by us and tested as potential anti-cancer drugs [Most of the tested 1,3,4-thiadiazole derivatives  and DG (3.28 Å). 3-Methoxyphenyl and 2-bromophenyl cores make the number of lipophilic interactions  with the nucleosides. Arg122 binds to Br by a halogen bond with the length 2.61 Å. Summary interaction energy increases owing to the carbon-hydrogen bond and Pi-donor hydrogen bond.One of the most active compounds SA14 and SA15 allow considered as interesting building blocks for further development of potent topoisomerase IV and DNA gyrase inhibitors.As a result of in silico simulation 1H NMR and 13C NMR spectra were recorded on the Bruker Avance 300  in DMSO-d6. IR spectra were recorded on Spectrometer FT-IR Nicolett 8700  The melting points were determined on the Stuart SMP50 melting point apparatus  and are uncorrected. The purity of the compounds and the progress of the reaction were monitored by TLC . We used the solvent system CHCl3/EtOH . The elemental analyses were determined by a Perkin Elmer 2400 Series II CHNS/O analyzer .All of the substances were purchased from Sigma-Aldrich  and were used without further purification. The SA1-SA12 and ST1-ST12 were obtained and described in our previous work [Compounds ous work .SA16) or 1 h (for the rest derivatives). Compound SA16 immediately precipitated. The solution was then cooled to room temperature until the product precipitated. The resulting solid was filtered off and washed with water and diethyl ether.0.01 mol of 3-methoxybenzhydrazide and 5 mL of 96% ethanol were placed in a round bottom flask. It was heated under reflux until a clear solution was obtained. Next, an equimolar amount of the appropriate aryl isothiocyanate was added. The mixture was heated at the boiling point for 30 min -1-(3-methoxyphenyl) thiosemicarbazide (SA13)−1) KBr: 3151 (NH), 2919 , 1666 (C=O), 1579 (CH arom.), 1336 (C=S), 1257 (C-O-C). 1H NMR (DMSO-d6)δ(ppm): 1.32 , 3.82 , 4.01 , 6.88 , 7.14–7.16 , 7.26 , 7.41 , 7.51–7.54 , 9.61 , 9.68 , 10.49 . 13C NMR (DMSO-d6) δ (ppm): 15.1; 55.8; 63.5; 113.5; 114.1; 118.1; 120.6; 128.1; 129.9; 132.4; 134.4; 156.5; 159.5; 166.2. Elemental analysis for C17H19N3O3S. Calculated: C 59.11; H 5.54; N 12.17. Found: C 59.29; H 5.77; N 12.43.Yield 71%, m.p.188–191 °C. IR (cm4-(2-Bromophenyl)-1-(3-methoxyphenyl) thiosemicarbazide (SA14)−1) KBr: 3187 (NH), 2965 , 1678 (C=O), 1582 (CH arom.), 1332 (C=S), 1285 (C-O-C). 1H NMR (DMSO-d6) δ(ppm): 3.82 , 7.14–7.22 , 7.37–7.39 , 7.41–7.43 , 7.45–7.51 , 7.51–7.56 , 7.65 , 9.64 , 9.85 , 10.61 . 13C NMR (DMSO-d6) δ (ppm): 55.77; 113.7; 118.2; 120.7; 122.7; 128.1; 128.7; 130.0; 131.3; 132.9; 134.3; 153.2, 159.5. Elemental analysis for C15H14BrN3O2S. Calculated: C 47.37; H 3.71; N 11.05. Found: C 47.60; H 3.83; N 11.35.Yield 80%, m.p.142–145 °C. IR (cm4-(3-Bromophenyl)-1-(3-methoxyphenyl) thiosemicarbazide (SA15)−1) KBr: 3150 (NH), 2959 , 1667 (C=O), 1583 (CH arom.), 1351 (C=S), 1295 (C-O-C). 1H NMR (DMSO-d6) δ(ppm): 3.82 , 7.16–7.17 , 7.30  7.34–7.36 , 7.43 , 7.51–7.55 , 7.72 , 9.90 , 10.56 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 113.6; 118.2; 120.6; 125.2; 128.3 , 130.1 ; 134.2; 141.4; 159.6; 166.2. Elemental analysis for C15H14BrN3O2S. Calculated: C 47.37; H 3.71; N 11.05. Found: C 47.50; H 3.65; N 11.40.Yield 79%, m.p.165–167 °C. IR (cm4-(4-Bromophenyl)-1-(3-methoxyphenyl) thiosemicarbazide (SA16)−1) KBr: 3150 (NH), 2969 , 1664 (C=O), 1585 (CH arom.), 1346 (C=S), 1259 (C-O-C). 1H NMR δ(DMSO-d6) δ(ppm): 3.81 , 7.13–7.17 , 7.39–7.44 , 7.50–7.54 , 9.88 , 10.59 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 113.5; 118.2; 120.6; 127.1; 129.9; 131.3; 133.7; 139.1; 159.5; 166.1. Elemental analysis for C15H14BrN3O2S. Calculated: C 47.37; H 3.71; N 11.05. Found: C 47.52; H 3.85; N 11.35.Yield 66%, m.p.173–175 °C.IR -1-(3-methoxyphenyl) thiosemicarbazide (SA17)−1) KBr: 3196 (NH), 2936 , 1668 (C=O), 1582 (CH arom.), 1345 (C=S), 1259 (C-O-C). 1H NMR (DMSO-d6) δ (ppm): 3.87 , 7.13–7.16 , 7.39–7.44 , 7.52–7.55 , 7.66 , 9.66 , 9.95 , 10.62 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 113.7; 118.2; 120.7; 127.7; 129.2; 129.9; 131.9; 132.7; 133.0; 134.2; 136.7; 159.5; 166.4; 182.5. Elemental analysis for C15H13Cl2N3O2S. Calculated: C 48.66; H 3.54; N 11.35. Found: C 48.86; H 3.75; N 11.70.Yield 55%, m.p.172–175 °C. IR (cm1-(3-Methoxyphenyl)-4- thiosemicarbazide (SA18)−1) KBr: 3164 (NH), 2961 , 1689 (C=O), 1583 (CH arom.), 1329 (C=S), 1267 (C-O-C). 1H NMR (DMSO-d6) δ (ppm): 2.13 , 2.26 , 3.80 , 6.97–7.02 , 7.11–7.14 , 7.35-7.42 , 7.50–7.53 , 9.48 , 9.76 , 10.49 . 13C NMR (DMSO-d6) δ (ppm): 18.1; 21.1; 55.8; 113.7; 118.0; 120.7; 126.8; 129.1; 131.0; 134.4; 136.0; 136.1; 159.5; 166.3; 182.3. Elemental analysis for C17H19N3O4S. Calculated: C 56.50; H 5.30; N 11.63. Found: C 56.83; H 5.43; N 11.70.Yield 62%, m.p.165–167 °C. IR  was added dropwise. The reaction mixture was stirred until the precipitate dissolved. Next, the solution was left for 2 h at room temperature. Then, crushed ice was added to the reaction flasks and mixed intensively. The precipitate formed which was allowed to dissolve the ice at room temperature. The solid product was filtered off, dried thoroughly with filter paper, and crystallization from butanol.Detailed physicochemical properties of novel 1,3,4-thiadiazoles:2-(4-Ethoxyphenylamino)-5-(3-methoxyphenyl)-1,3,4-thiadiazole (ST13)−1) KBr: 3191 (NH), 2838 , 1608 (C=N), 1592 (CH arom.), 1278 (C-O-C), 761 (C-S). 1H NMR (DMSO-d6) δ (ppm):1.32 , 3.83 , 4.00 , 6.93 , 7.03–7.07 , 7.35–7.39 , 7.41–7.44 , 7.53 , 10.34 . 13C NMR (DMSO-d6) δ (ppm): 15.2; 55.8; 63.7; 111.7; 115.4; 116.4; 119.9; 130.9; 132.2; 134.4; 154.5; 157.0; 160.1; 165.3. Elemental analysis for C17H17N3O2S. Calculated: C 62.36; H 5.23; N 12.83. Found: C 62.48; H 5.34; N 12.85.Yield 37% m.p.171–173 °C. IR (cm2-(2-Bromophenylamino)-5-(3-methoxyphenyl)-1,3,4-thiadiazole (ST14)−1) KBr: 3163 (NH), 2833 , 1648 (C=N), 1578 (CH arom.), 1262 (C-O-C), 757 (C-S). 1H NMR (DMSO-d6) δ(ppm): 3.83 , 7.06–7.09 , 7.11 , 7.37–7.39 , 7.40–7.45 , 7.70 , 10.60 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 111.8, 114.8 ; 115.6; 116.5 ; 119.8; 123.4, 124.0; 125.5; 126.2; 129.0 ; 129.8; 130.9; 132.0; 133.6 ; 139.3; 159.5; 160.1; 168.3. Elemental analysis for C15H12BrN3OS. Calculated: C 49.73; H 3.34; N 11.60. Found: C 50.01; H 3.54; N 11.86.Yield 14%, m.p.102–105 °C. IR (cm2-(3-Bromophenylamino)-5-(3-methoxyphenyl)-1,3,4-thiadiazole (ST15)−1) KBr: 3190 (NH), 2833 , 1625 (C=N), 1581 (CH arom.), 1266 (C-O-C), 749 (C-S). 1H NMR (DMSO-d6) δ(ppm): 3.84 , 7.07–7.11 , 7.20 , 7.32 , 7.42–7.44 , 7.48–7.51 , 8.10 , 10.79 . 13C NMR (DMSO-d6) δ (ppm): 55.8, 111.9; 116.8 ; 120.1 ; 122.5; 124.9; 130.9; 131.5; 131.8; 142.3; 158.6; 160.1; 164.1. Elemental analysis for C15H12BrN3OS. Calculated: C 49.73; H 3.34; N 11.60. Found: C49.85; H 3.45; N 11.80. Yield 28%, m.p.188–190 °C. IR (cm2-(4-Bromophenylamino)-5-(3-methoxyphenyl)-1,3,4-thiadiazole (ST16)−1) KBr: 3150 (NH), 2832 , 1664 (C=N), 1598 (CH arom.), 1261 (C-O-C), 751 (C-S). 1H NMR (DMSO-d6) δ (ppm): 3.84 , 7.08–7.10 , 7.41–7.45 , 7.54–7.55 , 7.64–7.66 , 10.70 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 113.6; 118.2; 120.6; 128.4; 129.9; 131.2; 134.2; 139.2; 159.5; 166.2. Elemental analysis for C15H12BrN3OS. Calculated: C 49.73; H 3.34; N 11.60. Found: C 49.94; H 3.38; N 11.68.Yield 17%, m.p.218–220 °C. IR -5-(3-methoxyphenyl)-1,3,4-thiadiazole (ST17)−1) KBr: 3130 (NH), 2838 , 1608 (C=N), 1563 (CH arom.), 1285 (C-O-C), 779 (C-S). 1H NMR (DMSO-d6) δ (ppm): 3.84 , 7.08–7.10 , 7.28–7.30 , 7.39–7.40 , 7.45–7.47 , 7.47–7.49 , 8.36–8.39 . 13C NMR (DMSO-d6) δ (ppm): 55.8; 111.9; 116.6; 119.9; 123.0; 123.9; 127.3; 128.4; 129.5; 130.9; 131.8; 160.1; 164.7. Elemental analysis for C15H11Cl2N3OS. Calculated: C 51.15; H 3.15; N 11.93. Found: C 51.36; H 3.34; N 11.98.Yield 23%, m.p.163–165 °C. IR (cm5-(3-Methoxyphenyl)-2--1,3,4-thiadiazole (ST18)−1) KBr: 3153 (NH), 2829 , 1634 (C=N), 1583 (CH arom.), 1259 (C-O-C), 766 (C-S). 1H NMR (DMSO-d6) δ (ppm): 2.25 , 2.27 , 3.82 , 7.03 , 7.04–7.06 , 7.08–7.09 , 7.33–7.34 , 7.40 , 7.60 . 13C NMR (DMSO-d6) δ (ppm): 18.2; 20.9; 55.7; 111.6; 116.4; 119.7; 123.1; 127.7; 130.9; 131.9; 132.2; 134.5; 137.2; 157.1; 160.1; 167.9. Elemental analysis for C17H17N3O3S. Calculated: C 59.46; H 4.99; N 12.24. Found: C 59.56; H 5.21; N 12.45.Yield 34%, m.p.174–176 °C. IR  and three Gram-negative reference bacteria . These bacterial strains cause the most common infections among humans. To perform the assay, all microorganisms were placed in sterile physiological saline (0.85% NaCl) to obtain a suspension of the optical density of the 0.5 McFarland standard; 1.50 × 10 8 colony-forming units (CFUs)/mL. A solution of the test compounds was prepared in Dimethyl sulfoxide (DMSO) at a concentration of 50 mg/mL. The solutions were then diluted with Mueller-Hinton broth to obtain a solution with a concentration of 2000 µg/mL. Then, using the two-fold dilution method in broth, the test compounds were introduced into the wells of the microplate to give a final concentration of 0.49 to 1000 µg/mL. Negative control without tested compounds was used. Cefuroxime and ciprofloxacin in a concentration 0.007–15.625 µg/mL were used as a positive controls. These antibiotics are most commonly used in the outpatient treatment of bacterial infections.The antimicrobial activity of the thiosemicarbazides and 1,3,4-thiadiazoles series was tested against four Gram-positive reference strains -1-(3-methoxyphenyl) thiosemicarbazide SA1, with a MIC value of 62.5 µg/mL against both strains. The compound that showed the highest activity against all tested Gram-positive bacteria strains  was SA11, thiosemicarbazide having a 3-trifluoromethylphenyl substituent. A molecular docking study showed that the probable mechanism of action of the tested compounds is the inhibition of DNA gyrase and topoisomerase IV. Basically, the results obtained by us indicate a weak antimicrobial activity of the studied groups of compounds. It may be related both to the structure of the compounds and the bacterial strains used. In the future, it is possible to extend the research to other bacteria and introduce other pharmacophore groups  to the phenyl ring.Continuing our investigation on the search for compounds with significant antibacterial activity, we obtained a number of new thiosemicarbazide and 1,3,4-thiadiazole derivatives with a 3-methoxyphenyl substituent. We tested them against selective Gram-positive and Gram-negative bacteria strains. Additionally, we included the previously obtained derivatives from these groups in the biological investigation. All tested compounds showed no activity against Gram-negative bacteria. Most of the tested thiosemicarbazides showed moderate activity against all strains of Gram-positive bacteria. The highest antibacterial activity against two bacterial