Isolation and Synthesis of Methyl Bovinate, an Unusual Pulvinic Acid Derivative from Suillus bovinus (Basidiomycetes)

Abstract

Cultures and fruit bodies of Suillus bovinus produce the pulvinic acid derivative methyl bovinate (4), which contains an extra carbonyl group that bridges ring A of methyl variegatate with the hydroxy group at the central butenolide ring. This unprecedented structure was deduced from the spectroscopic data and confirmed by total synthesis via a grevillin intermediate. In this synthesis, the menthyl group was used for carboxyl protection.