Rearrangement in Stereoretentive Syntheses of Menthyl Chloride from Menthol: Insight into Competing Reaction Pathways through Component Quantification Analysis
作者:Lukas Hintermann、Kit Ming Wong
DOI:10.1002/ejoc.201700677
日期:2017.10.10
three regioisomeric tertiary chloromenthanes (9, 10, 11), and both a secondary (12) and tertiary chloride (16) derived from ψ-menthane (1-isobutyl-3-methylcyclopentane). A scheme of rearrangement pathways starting from a common menthyl carbenium ion pair is derived. The effect of purification protocols on crude 2 has been studied quantitatively. Either selective solvolysis of tertiary sideproducts (98
对映纯试剂薄荷基氯 (2) 通常由 (-)-(1R)-薄荷醇 (1) 与 Lucas 试剂(ZnCl2 浓盐酸水溶液)在立体保留反应中制备,该反应似乎没有伴随的重排。最近通过 TiCl4 催化从氯亚硫酸薄荷酯中挤出 SO2 合成 2 也是如此 (3)。现在已经通过定量 1H 和 13C NMR 方法分析了两种合成的产物,并且所有反应组分都已鉴定到≤0.5 mol% 的水平。任一反应都伴随着达到 18-25 mol% 的相当程度的阳离子重排。除了预期的 2、新薄荷酰氯 (4) 和五种重排产物外,还鉴定了三种区域异构叔氯薄荷烷 (9, 10, 11),以及衍生自ψ-薄荷烷(1-异丁基-3-甲基环戊烷)的仲氯化物(12)和叔氯化物(16)。推导出了从常见的薄荷基碳鎓离子对开始的重排途径方案。已定量研究纯化方案对粗品 2 的影响。三级副产物的选择性溶剂分解(纯度 98 mol%)或低温结晶(纯度≥97