Chiral Brønsted acid catalyzed enantioselective allenylation of aldehydes.

A versatile and highly enantioselective chiral Brønsted acid-catalyzed allenylation of aldehydes with propargyl borolane is reported. The reaction is shown to be practical and quite general with a broad substrate scope covering aryl, heteroaryl, α,β-unsaturated, and aliphatic aldehydes.