Enantioselective Butenolide Preparation for Straightforward Asymmetric Syntheses of γ-Lactones – Paraconic Acids, Avenaciolide, and Hydroxylated Eleutherol
作者:Stefan Braukmüller、Reinhard Brückner
DOI:10.1002/ejoc.200500961
日期:2006.5
occurring γ-lactones (+)-methylenolactocin (13) and its enantiomer, (+)-protolichesterinic acid (14) and its enantiomer, (+)-rocellaric acid (15), and the methylene bis(γ-lactone) (–)-avenaciolide (16) were synthesized with 95–98 % ees in very few steps. Enantiocontrol was imposed by the asymmetric dihydroxylation of trans-configured β,γ-unsaturated carboxylic esters (namely compounds 1i, 1j, and 1n)
天然存在的 γ-内酯 (+)-亚甲基乳酸菌素 (13) 及其对映体、(+)-protolichesterinic acid (14) 及其对映体、(+)-rocellaric acid (15) 和亚甲基双(γ-内酯) (-)-avenaciolide (16) 是通过很少的步骤合成的,具有 95-98% 的 ee。对映控制是由反式构型的 β,γ-不饱和羧酸酯(即化合物 1i、1j 和 1n)与 AD mix-α® [对于左旋目标结构,除了 (-)-avenaciolide 外] 或AD mix-β® [用于右旋目标结构加 (-)-avenaciolide]。β,γ-不饱和羧酸酯 1e 需要更多的氧化剂和助剂来生产羟基内酯 R,R-3e,它是萘并-γ-内酯 (+)-9-羟基戊二烯的前体 (12; 96 % ee) . (© Wiley-VCH Verlag GmbH & Co. KGaA,