Gold catalysis: benzanellation versus alkylidenecyclopentenone synthesis

A series of different furan-yn-ols were prepared by a three-step sequence. Their reaction with Gagosz's catalyst Ph3PAuNTf2 depends strongly on the substitution pattern of the substrate and the quality of the leaving group. Benzofurans, alkylidenecyclopentenones or Meyer-Schuster type products can be obtained. Improving the leaving group quality leads to the preferred formation of benzofurans.