Total Syntheses of (−)??Grandinolide and (−)??Sapranthin by the Sharpless Asymmetric Dihydroxylation of Methyl trans??3??Pentenoate: Elucidation of the …

C Harcken, R Brückner, E Rank

Index: Harcken, Christian; Brueckner, Reinhard; Rank, Elisabeth Chemistry - A European Journal, 1998 , vol. 4, # 11 p. 2342 - 2352

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Citation Number: 42

Abstract

Abstract The commercially available title ester (1) was converted into the phytochemicals (−)- grandinolide (3) and (−)-sapranthin (4) through trans-selective alkylations of the “dianions” derived from enantio-enriched β-hydroxy-γ-lactones and excess LDA. Lactone 2 was obtained from 1 through an asymmetric dihydroxylation (1 step, 78% ee). Through alkylation, the “dianion” of 2 gave 3. The OH group of lactone 2 was also inverted. Deprotonation of ...