General conjugate-addition method for the synthesis of enantiomerically pure lignans. Total synthesis of (-)-and (+)-burseran,(-)-dehydroxycubebin,(-)-trichostin,(-)- …

N Rehnberg, G Magnusson

Index: Rehnberg, Nicola; Magnusson, Goeran Journal of Organic Chemistry, 1990 , vol. 55, # 14 p. 4340 - 4349

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Citation Number: 49

Abstract

Conjugate addition of benzylic diphenyldithioacetal anions to enantiomerically pure (-)-(2R)- and (+)-(2S)-2-(benzyloxy)-2, 5-dihydro-4-[3, 4-(methylenedioxy) benzoyl] furan (2r and 2s) gave complete lignan skeletons of the dibenzylbutane class. Desulfurization followed by hydrogenolysis and, when appropriate, oxidation gave the title enantiomerically pure (> 99% ee) lignans 45-50 in 24-35% overall yields from 2r and 2s.