Vinylogous Addition of Siloxyfurans to Benzopyryliums: A ConciseApproach to the Tetrahydroxanthone Natural Products

摘要

A concise approach to the tetrahydroxanthone natural products has been developed employing vinylogous addition of siloxyfurans to benzopyryliums and a late stage Dieckmann cyclization. Using this methodology, chiral, racemic forms of the natural products blennolides B and C have been synthesized in a maximum of four steps from a 5-hydroxychromone substrate. The regio- and diastereoselectivity of vinylogous additions was probed using computational studies which suggest involvement of Diels-Alder-like transition states.