Organomercury chemistry of iridoid glucosides. Part 2. Chemoselective methoxymercuriation-demercuriation of aucubin: a new approach to optically active cyclopentenols

Abstract

Methoxymercuriation of aucubin (1) occurred chemoselectively at the enol ether Δ³ double bond with formation, after the demercuriation of the organomercurial intermediate (6), of the chiral cyclopentenoid O-methyl ethers (5), (12), and (13). The mechanism proposed for the demercuriation of (6) was supported by selective formation of the three products on adjusting the pH of the reduction medium. The structural features of (5), (12), and (13) make them useful precursors for syntheses of bioactive cyclopentanoid compounds.