Asymmetric Allylboration of Ketones Catalyzed by Chiral Diols

Significance

The enantioselective allylation of carbonyl compounds is a widely used synthetic method for the creation of asymmetric centers. The catalytic allylation of ketones still represents a challenging task, as not many methods are developed for this reaction and even fewer are really practical. Herein, the authors reported a simple, highly efficient and inexpensive protocol for the allylation and crotylation of a variety of ketones, including acetophenones, enones and ynones. Readily available 3,3′-dibromo-BINOL as catalyst and allylic diisopropoxyboranes as allylating reagents were used. The yields and enantio­selectivities are very high in almost all cases. The method can be potentially extended to perform a crotylation reaction, which demonstrates its great perspectives in synthetic organic chemistry.