Tandem Ring-Closing/Cross-Metathesis Approach for the Synthesis of Synargentolide B and Its Stereoisomers

Abstract

The stereoselective syntheses of synargentolide B and its three stereoisomers have been accomplished from L-(+)- and D-(–)-diethyl tartrates, D-ribose, and D-mannitol as chiral pool starting materials. The key step was a tandem ring-closing/cross-metathesis reaction in which lactone formation and fragment coupling were accomplished in one pot. The spectroscopic data of synthetic product 2c were in agreement with those reported for the natural product. Synargentolide B isolated by Rivett et al. and the compound isolated by Pereda-Miranda et al. are not diastereomers, but rather they are identical.