Amide-Directed Catalytic Asymmetric Hydroboration of Trisubstituted Alkenes

作者：Smith Sean M; Takacs James M^*

来源：Journal of the American Chemical Society, 2010, 132(6): 1740-+.

DOI：10.1021/ja908257x

Rhodium-catalyzed hydroborations of trisubstituted alkenes are generally slow and often suffer from competing alkene isomerization. In contrast, the trisubstituted alkene moieties contained within the framework of a beta,gamma-unsaturated unsaturated amide undergo facile reaction, perhaps facilitated by carbonyl directing effects and two-point binding of the substrate to the rhodium catalyst. Stereo isomeric substrates, for example, (E)- and (Z)-3, cleanly give rise to diastereomeric products, and thus the rhodium-catalyzed reaction is stereospecific. In addition, simple TADDOL-derived phenyl monophosphite ligands in combination with Rh(nbd)(2)BF(4) afford highly enantioselective catalysts (seven examples, 91-98% ee). These catalysts provide an alternative methodology to prepare Felkin or anti-Felkin acetate-aldol products and related derivatives that are obtainable from the intermediate chiral organoboranes.

• 出版日期2010-2-17