A new procedure for highly stereoselective and regioselective synthesis of 2-ethynyl-3-hydroxytetrahydropyran derivatives based on alkyne-Co2(CO)6 complex
作者:Chisato Mukai、Yu-ichi Sugimoto、Yoshitaka Ikeda、Miyoji Hanaoka
DOI:10.1016/s0040-4020(97)10357-x
日期:1998.1
cis-2-ethynyl-3-hydroxytetrahydropyran derivatives via endo mode cyclization pathway. cis-Congeners, cis-3 afforded the corresponding trans tetrahydropyran derivatives exclusively. This novel cyclization has been found to proceed with retention of configuration at the propynyl stereogenic center. Requirement for stereoselectivity in cyclization was discussed.
用Co 2(CO)8处理反式环氧化合物3得到相应的钴配合物,随后将其在-78°C下暴露于催化量的BF 3 ·OEt 2,仅提供顺式-2-乙炔基-3-羟基四氢吡喃衍生物通过内模环化途径。顺-Congeners,顺式- 3,得到相应的反式仅限于四氢吡喃衍生物。已经发现这种新颖的环化作用是在丙炔立体定位中心保留构型而进行的。讨论了环化中立体选择性的要求。