Enantioselective intramolecular cyclization of alkynyl esters catalyzed by a chiral Brønsted base

An enantioselective intramolecular cyclization reaction of alkynyl esters was developed, which employs a Brønsted base catalyst generated in situ from a chiral Schiff base and t-BuOK. This reaction is a rare example of the enantioselective intramolecular addition of simple ester enolates to alkynes under Brønsted base catalysis.