Absolute configuration of atropisomeric m-terphenyl-type flavan-3-ols

Abstract

The absolute configuration about both biphenyl linkages in a series of atropisomeric (2R,3S)-2,3-trans-3-acetoxy-6,8-bis-[(2R,3S)-2,3-trans-3-acetoxy-3′,4′,7,8-tetramethoxyflavan-5-yl]-3′,4′,5,7-tetra-methoxyflavans {[5,6:5,8]-bis-(+)-[mesquitol]-(+)-catechins} were established by nuclear Over-hauser effect difference spectroscopy. This approach is based on association of relevant heterocyclic acetoxy protons with aromatic methoxy groups in close proximity of the bonding axes.