Extremely Active Organocatalysts Enable a Highly Enantioselective Addition of Allyltrimethylsilane to Aldehydes

Abstract

The enantioselective allylation of aldehydes to form homoallylic alcohols is one of the most frequently used carbon-carbon bond-forming reaction in chemical synthesis and, for several decades, has been a testing ground for new asymmetric methodology. However, a general and highly enantioselective catalytic addition of the inexpensive, nontoxic, air- and moisture-stable allyltrimethylsilane to aldehydes, the Hosomi-Sakurai reaction, has remained elusive. Reported herein is the design and synthesis of a highly acidic imidodiphosphorimidate motif (IDPi), which enables this transformation, thus converting various aldehydes with aromatic and aliphatic groups at catalyst loadings ranging from 0.05 to 2.0 mol % with excellent enantioselectivities. Our rationally constructed catalysts feature a highly tunable active site, and selectively process small substrates, thus promising utility in various other challenging chemical reactions.

Keywords: allylic compounds; enantioselectivity; nucleophilic addition; organocatalysis; silanes.