9-Demethyl-9-haloretinals by Wadsworth−Emmons Coupling− Easy Preparation of Pure (all-E), (9Z) and (11Z) Isomers
作者:Yajie Wang、Wei Sein Woo、Ineke van der Hoef、Johan Lugtenburg
DOI:10.1002/ejoc.200400005
日期:2004.5
quantitative yield as a mixture of (9Z) and (all-E) isomers. Even the corresponding fluoro derivative could be obtained in good yield as (9Z) and (all-E) isomers. In the case of a double bond having a halogen substituent, the IUPAC rules have the (E) nomenclature for a cis double bond and the (Z) for a trans double bond. Simple column chromatography gave the pure (9Z) and (all-E) form. Optimizing the Wadsworth−Emmons
5-(2',6',6'-Trimethyl-1'-cyclohexen-1'-yl)-4-penten-2-yn-1-al 以β-紫罗兰酮为原料,一锅法制备几乎定量的产量。使用 1,4- 亲核加成反应,相应的 9-Cl、9-Br、9-I β-亚亚乙基乙醛体系可以作为(9Z)和(全 E)异构体的混合物一步以定量收率获得。甚至相应的氟衍生物也可以作为(9Z)和(全-E)异构体以良好的收率获得。在双键具有卤素取代基的情况下,IUPAC 规则对顺式双键使用 (E) 命名法,对反式双键使用 (Z) 命名法。简单的柱色谱得到纯的 (9Z) 和 (all-E) 形式。优化 Wadsworth-Emmons 偶联得到相应的 (all-E)- 和 (9Z)- 视黄腈定量产率。随后的 DIBAL-H 减少产生相应的视网膜。为了制备对视觉至关重要的 (11Z) 异构体,我们发现 Wadsworth-Emmons