Enantio- and Diastereoselective 12-Additions to α-Ketoesters with Diborylmethane and Substituted 11-Diborylalkanes

摘要

Catalytic enantioselective synthesis of boronate-substituted tertiary alcohols through additions of diborylmethane and substituted 1,1-diborylalkanes to α-ketoesters is reported. The reactions are catalyzed by readily available chiral phosphine–copper(I) complexes and produce β-hydroxyboronates containing up to two contiguous stereogenic centers in up to 99:1 er, and >20:1 dr. The utility of the organoboron products is demonstrated through several chemoselective functionalizations. Evidence indicates reactions occur via enantio-enriched α-boryl-Cu-alkyl intermediate.