First Stereocontrolled Syntheses of Unsymmetrically Substituted Bislactone Lignans: Stereocontrolled Syntheses of Four Possible Isomers of Methyl 4,8-Dioxoxanthoxylol
摘要:
An efficient method for stereocontrolled syntheses of the unsymmetrically substituted bislactone subgroup of the furofuran lignan has been developed based on a stereoselective aldol reaction of the acid anhydride 8 or 9 and an aromatic aldehyde employing methyl 4,8-dioxoxanthoxylol (1a), 4,8-dioxofargesin (1b), methyl 4,8-dioxopiperitol (2a) and their isomer 3a as the representative examples of the axial-equatorial 1, diequatorial 2, and diaxial 3 types of this series.