A highly selective cobalt-catalyzed carbonylative cyclization of internal alkynes with carbon monoxide and organic thiols
作者:Yoshihiro Higuchi、Shinya Higashimae、Taichi Tamai、Akiya Ogawa
DOI:10.1016/j.tet.2013.10.080
日期:2013.12
ineffective, cobalt carbonyl (Co2(CO)8) is an excellent catalyst for carbonylative cyclization of internal alkynes with carbon monoxide. When Co2(CO)8-catalyzed reactions of internal alkynes with organic thiols are conducted in acetonitrile under 4 MPa pressure of carbon monoxide, thiolative lactonization of internal alkynes successfully takes place with incorporation of two molecules of CO. This carbonylation
尽管事实上许多过渡金属催化的有机硫化合物与内部炔烃的反应均无效,但羰基钴(Co 2(CO)8)是内部炔烃与一氧化碳羰基化环化的极佳催化剂。当Co 2(CO)8一氧化碳在4 MPa的压力下,在乙腈中进行内部炔烃与有机硫醇的催化反应,通过结合两个CO分子成功地完成了内部炔烃的硫醇化内酯化反应。这种羰基化作用为制备相应的α,β提供了有用的工具-不饱和γ-硫代-γ-内酯(丁烯内酯衍生物),收率高。在不对称炔烃的情况下,例如2-辛炔和6-甲基-2-庚炔,硫醇化内酯化以适度的区域选择性进行,得到丁烯酰内酯衍生物,其羰基优先结合在受阻较小的炔碳上。还讨论了有关目前的巯基内酯化的机制途径。