An enantioselective synthesis of the resorcylic acid lactone L-783,277 via addition of an acetylide anion to a tethered weinreb amide

Treatment of the terminal acetylene 12, readily obtained from the previously reported acid 10, with LiHMDS resulted in a novel macrocyclization reaction to give the cycloalkyne 13. Subjection of compound 13 to hydrogenation under Lindlar-type conditions afforded the Z-configured enone 14 that could be converted into the resorcylic acid lactone 4 upon treatment with BCl₃ in CH₂Cl₂ at -78°C.