(2S*,4R*,5R*)-4-chloro-2-methoxy-4,5-dimethyltetrahydropyran | 135695-89-5

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 氧烷类
• 英文名称: (2S*,4R*,5R*)-4-chloro-2-methoxy-4,5-dimethyltetrahydropyran
• 英文别名: (2S,4R,5R)-4-chloro-2-methoxy-4,5-dimethyloxane
• CAS: 135695-89-5
• 化学式: C₈H₁₅ClO₂
• 分子量: 178.659
• InChiKey: RRRPFVCATKJVJN-GJMOJQLCSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  1.9
• 重原子数：
  11
• 可旋转键数：
  1
• 环数：
  1.0
• sp3杂化的碳原子比例：
  1.0
• 拓扑面积：
  18.5
• 氢给体数：
  0
• 氢受体数：
  2

反应信息

• 作为产物：
  描述：

  2,3-dimethylbut-3-en-1-ol 、 原甲酸三甲酯 在 四氯化锡 作用下， 以 二氯甲烷 为溶剂， 反应 1.0h， 以62%的产率得到(2S*,4R*,5R*)-4-chloro-2-methoxy-4,5-dimethyltetrahydropyran
  参考文献：
  名称：

  Chemistry of dioxenium cations. Synthetic and mechanistic studies on the stereocontrolled formation of tetrahydropyrans from homoallylic alcohols and ortho esters

  摘要：

  Despite their long history, dioxenium cations are underutilized reactive synthetic intermediates. It was found that ortho esters and homoallylic alcohols in the presence of Lewis acids provide 4-heterosubstituted pyranosides in a stereoselective manner. The mechanistic course of events was supported by control experiments and synthesis of a putative mixed ortho ester intermediate which exhibited identical reactivity. A transition state for termination of the dioxenium cation-olefin cyclization is proposed, involving intramolecular delivery of chloride by a coordinated tin species. Structure-reactivity relationships indicate that a cation-stabilizing substituent (alkyl or alkoxy) at the internal position of the olefin is required for cyclization. A variety of 3-alkyl-substituted homoallylic alcohols cyclize cleanly to substituted 2-alkoxytetrahydropyrans in good yield. beta-silyloxy silyl enol ethers were found to smoothly provide 4-oxotetrahydropyranosides when subjected to the same reaction conditions. For these substrates, the course of the cyclization proceeds in a different manner involving a rapid intermolecular Mukaiyama aldol condensation followed by transacetalization.

  DOI：

  10.1021/jo00021a043

文献信息

• Chemistry of dioxenium cations. Synthetic and mechanistic studies on the stereocontrolled formation of tetrahydropyrans from homoallylic alcohols and ortho esters
  作者：Francoise Perron-Sierra、Michele A. Promo、Van A. Martin、Kim F. Albizati

  DOI：10.1021/jo00021a043

  日期：1991.10

  Despite their long history, dioxenium cations are underutilized reactive synthetic intermediates. It was found that ortho esters and homoallylic alcohols in the presence of Lewis acids provide 4-heterosubstituted pyranosides in a stereoselective manner. The mechanistic course of events was supported by control experiments and synthesis of a putative mixed ortho ester intermediate which exhibited identical reactivity. A transition state for termination of the dioxenium cation-olefin cyclization is proposed, involving intramolecular delivery of chloride by a coordinated tin species. Structure-reactivity relationships indicate that a cation-stabilizing substituent (alkyl or alkoxy) at the internal position of the olefin is required for cyclization. A variety of 3-alkyl-substituted homoallylic alcohols cyclize cleanly to substituted 2-alkoxytetrahydropyrans in good yield. beta-silyloxy silyl enol ethers were found to smoothly provide 4-oxotetrahydropyranosides when subjected to the same reaction conditions. For these substrates, the course of the cyclization proceeds in a different manner involving a rapid intermolecular Mukaiyama aldol condensation followed by transacetalization.