Asymmetric Conjugate Addition of Boronates to N-Acylimines and β-Silyl-α,β-unsaturated Ketones Catalyzed by 3,3'-Disubstituted Binaphthols

Abstract

In order to extend the scope of asymmetric conjugate alkenylation catalyzed by 3,3′-disubstituted binaphthols, two classes of compounds were examined. Asymmetric 1,4-addition of alkenylboronates onto N-acylimines was investigated. Chiral allylic amides were obtained in good yields and high enantioselectivities. This represents one of the very few methods for synthesizing chiral allylic amides without the use of transition metal catalysts. Chiral binaphthol-catalyzed conjugate addition of alkenylboronates to -silyl--unsaturated ketones afforded highly enantioenriched chiral -silylcarbonyls. Asymmetric addition onto -silyl-enones is still a largely unexplored area, with only a handful of transition metal-catalyzed reactions reported. The first asymmetric reaction using these silicon-containing enones without using transition metal were described.