Synthesis of Enantiomerically Pure (−)-Wine Lactone Based on a Palladium-Catalyzed Enantioselective Allylic Substitution
作者:Eike J. Bergner、Günter Helmchen
DOI:10.1002/(sici)1099-0690(200002)2000:3<419::aid-ejoc419>3.0.co;2-n
日期:2000.2
The first enantioselective synthesis of enantiomerically pure (−)-wine lactone, (−)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation
首次对映异构纯 (-)-葡萄酒内酯 (-)-1a(各种白葡萄酒的香味成分)及其差向异构体 (+)-1b 进行了对映选择性合成。关键步骤是使用磷酰二氢恶唑 L1 或磷酰羧酸 L2 的钯配合物作为催化剂,用丙二酸二甲酯对 (±)-2-环己烯-1-基乙酸酯 (2) 进行烯丙基取代,随后脱羧、碘内酯化和消除,提供对映体纯双环内酯 (+)-7,总产率为 47%。通过用有机铜化合物进行 SN2' 型取代并通过烯醇化物烷基化非对映选择性引入甲基,从 (+)-7 得到内酯 (-)-1a,总产率为 43%。