Mechanistic insights into direct amide bond formation catalyzed by boronic acids: Halogens as Lewis bases

Abstract

(Figure Presented) Get the water out! DFT calculations predict water elimination from a tetrahedral intermediate to be the rate determining step in the title reaction. This transformation is calculated to be highly stereoselective, yielding cis amides as the kinetic products (see scheme). The superior activity of ortho-halophenyl boronic acids results from the Lewis basic character of halogen atoms. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.