An asymmetric propargylation of cyclopropanols

Despite significant achievements in the catalytic asymmetric propargylation of enol(ate) intermediates, the catalytic asymmetric propargylation of homo-enol(ate) or its equivalents is still underdeveloped. Recently, we disclosed an intramolecular enantioselective propargylation of cyclopropanols using a new PyBox-complexed copper catalyst, which allows efficient assembly of the naturally occurring cuparane core. Key points of this reaction are the formation of a monocopper allenylidene intermediate, followed by ring-opening cyclization of the cyclopropanol unit.