TANDEM MANGANESE(III)-BASED OXIDATIVE FREE-RADICAL CYCLIZATIONS TERMINATED BY ADDITION TO FURANS. FORMAL SYNTHESIS OF 15-ACETOXYPALLESCENSIN-A

Abstract

Reaction of β-keto ester 12 with 2 equiv. of Mn(OAc)32H2O in KOAc-buffered MeOH followed by acidic workup afforded 51% of tricyclic furan 14 indicating that oxidative cyclizations can be terminated by addition to furans. Reduction of 14 with LAH provided 7, completing a five-step formal synthesis of 15-acetoxypallescensin-A.