Sustainable Triazine-Based Dehydro-Condensation Agents for Amide Synthesis.
Conventional methods employed today for the synthesis of amides often lack of economic and environmental sustainability. Triazine-derived quaternary ammonium salts, e.g., 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM(Cl)), emerged as promising dehydro-condensation agents for amide synthesis, although suffering of limited stability and high costs. In the present work, a simple protocol for the synthesis of amides mediated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and a tert-amine has been described and data are compared to DMTMM(Cl) and other CDMT-derived quaternary ammonium salts (DMT-Ams(X), X: Cl- or ClO4-). Different tert-amines (Ams) were tested for the synthesis of various DMT-Ams(Cl), but only DMTMM(Cl) could be isolated and employed for dehydro-condensation reactions, while all CDMT/tert-amine systems tested were efficient as dehydro-condensation agents. Interestingly, in best reaction conditions, CDMT and 1,4-dimethylpiperazine gave N-phenethyl benzamide in 93% yield in 15 min, with up to half the amount of tert-amine consumption. The efficiency of CDMT/tert-amine was further compared to more stable triazine quaternary ammonium salts having a perchlorate counter anion (DMT-Ams(ClO4)). Overall CDMT/tert-amine systems appear to be a viable and more economical alternative to most dehydro-condensation agents employed today.
['Sole|Roberto|R|0000-0002-3208-2288', 'Gatto|Vanessa|V|0000-0003-2577-2974', 'Conca|Silvia|S|0000-0001-6123-6592', 'Bardella|Noemi|N|', 'Morandini|Andrea|A|', 'Beghetto|Valentina|V|0000-0001-8799-210X']
D000577:Amides D000588:Amines D001549:Benzamides D002264:Carboxylic Acids D060326:Chemistry Techniques, Synthetic D010472:Perchlorates D010627:Phenethylamines D010879:Piperazines D000644:Quaternary Ammonium Compounds D012997:Solvents D014227:Triazines
amide synthesis CDMT triazines sustainable dehydro-condensation agents