Diastereomeric Enols and Enol Derivatives of 8-Fluoro-5,11-dihydro-10H-dibenzo[a,d]cyclohepten-10-one with a Chiral 11-Substituent
作者:Frans Compernolle、Suzanne Toppet、Thierry Brossette、Hua Mao、Mohamed Koukni、Tomasz Kozlecki、Bart Medaer、Michel Guillaume、Yolande Lang、Stef Leurs、Georges J. Hoornaert
DOI:10.1002/ejoc.200500796
日期:2006.3
Aldol condensation of 8-fluoro-5,11-dihydro-10H-dibenzo[a,d]cyclohepten-10-one and (4S)-2,2-dimethyl-1,3-dioxolane-4-carbaldehyde provides access to the corresponding (E,Z)-α,β-unsaturated ketones with a (4R)-chiral 11-substituent. Subsequent hydrogenation affords a mixture of (11R)/(11S)-epimeric ketones, which undergoes base-catalysed equilibration resulting in selective crystallisation of the (11R)
8-氟-5,11-二氢-10H-二苯并[a,d]环庚烯-10-酮和(4S)-2,2-二甲基-1,3-二氧戊环-4-甲醛的羟醛缩合提供了获得相应的 (E,Z)-α,β-不饱和酮具有 (4R)-手性 11-取代基。随后的氢化提供 (11R)/(11S)-差向异构酮的混合物,其经历碱催化平衡,导致 (11R) 差向异构体的选择性结晶。烯醇中间体和无环烯醇衍生物显示为两个缓慢相互转换的构象异构体,具有 10,11-二取代环的高反转势垒。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)