Total synthesis of moracin C

Abstract

Moracin C has been synthesised by the most efficient route to date (10 steps and 12% overall yield). The relatively unexplored acid-induced, intramolecular migration of an acyl group from an ortho phenolic hydroxy to a benzylic hydroxy is used to synthesise o-hydroxybenzylphosphonium salts containing ester groups. The phosphonium salts are coupled with 3,5-dimethoxybenzoic acid. Intramolecular Wittig reaction then gives 2-arylbenzo[b]furans, bearing the key 1′,3′,5′ substitution pattern on the aryl ring. This discovery provides a concise route to polyphenolic benzo[b]furans that we expect to be of general utility.