Synthesis of Secondary and Tertiary Alkyl Boronic Esters by gem-Carboborylation: Carbonyl Compounds as Bis(electrophile) Equivalents.
An unprecedent gem-carboborylation of aldehydes and ketones provides access to various secondary and tertiary alkyl boronic esters. The addition of B2 pin2 to a carbonyl compound generates α-oxyl-substituted alkyl boron species. Organolithium and Grignard reagents are then applied as C nucleophiles for the 1,2-metalate rearrangement process. The organolithium reagents can also be generated by C-H lithiation or halogen/lithium exchange. The use of chiral ligands led to the generation of chiral alkyl boronic esters in enantioenriched form, demonstrating that the enantioselectivity of this transformation is catalyst-controlled.
['Shi|Dunfa|D|', 'Wang|Lu|L|', 'Xia|Chungu|C|', 'Liu|Chao|C|http://orcid.org/0000-0002-2521-924X']
alkyl boronic esters boron asymmetric catalysis carboborylation copper catalysis