Asymmetric Allylation of Aldehydes Catalyzed by a Chiral Indium(III)-BINOL Complex

asymmetric catalysis - allylation - trialkylallyl­-stannanes - indium - aldehydes - homoallylic alcohols

Significance

The first chiral indium(III)-catalyzed allylation reaction of aldehydes is disclosed. By using catalytic InCl₃/(S)-BINOL, highly enantioselective formation of homoallylic alcohols was achieved using allyltributylstannane.

Comments

This allylation protocol developed is relatively simple, mild and affords excellent enan­tioselectivity with both aromatic and aliphatic aldehydes. The most likely drawback is the high toxicity of organotin reagents. Further studies to determine the scope of the reaction with a variety of aromatic aldehydes is required. Preliminary mechanistic studies revealed that the active chiral Lewis acid catalyst is a BINOL-In(III)-allyl complex. There are many asymmetric allylation reagents or allylation catalysts present in the literature (for a review see: S. E. Denmark, J. Fu Chem. Rev. 2003, 103, 2763-2794).