Facile synthesis of natural moracin compounds using PD(OAC)2/P(TBU)3-HBF4 as a sonogashira coupling reagent

Abstract

An efficient and practical synthesis of natural moracins, which have diverse range of biological properties including anticancer, antioxidant, and antibacterial activities, has been achieved using Pd(OAc)2/P(tBu)3-HBF4 as a Sonogashira coupling reagent which solved the unreactive problems in case of higher electron density of haloaryl compounds in the reaction. Lowering electron density of halophenol with acetylation and changing Sonogashira coupling reagent from PdCl2(PPh3)2 to Pd(OAc)2/P(tBu)3-HBF4 smoothly produce the benzofuran structures in the syntheses of moracins M, N and S. The electron deficient halobenzaldehyde, however, easily forms the benzofuran using original Sonogashira conditions, and utilized for the first synthesis of moracin Y.