Total synthesis of quasi-symmetric dihydrofuran lignans (−)-ribesin A and B isolated from Ribes nigrum leaves

Abstract

Dihydrofuran lignans ribesin A (1) and ribesin B (2) isolated from Ribes nigrum leaves were chemically synthesized for the first time using oxa-Michael addition–carbocyclization and double-bond migration as key steps. However, the NMR data of synthesized ribesin B (2) with vanillin scaffolds were slightly inconsistent with those of reported ribesin B (2). Through further synthetic study, the structure of natural ribesin B (2) was revised to that of 3, which has unique isovanillin scaffolds. Moreover, the asymmetric total synthesis of natural products ribesin A (1) and ribesin B (3) was achieved using chiral propargyl alcohols as the starting materials prepared via lipase-catalyzed kinetic resolution.