Recent Advances in “Formal” Ruthenium-Catalyzed [2+2+2] Cycloaddition Reactions of Diynes to Alkenes
作者:Silvia García-Rubín、Jesús A. Varela、Luis Castedo、Carlos Saá
DOI:10.1002/chem.200801088
日期:2008.10.29
[2+2+2] cycloaddition of 1,6-diynes to alkenes gave bicyclic 1,3-cyclohexadienes in relatively good yields. When terminal 1,6-diynes 1 were used, two isomeric bicyclic 1,3-cyclohexadienes 4 or 6 were obtained, depending on the acyclic or cyclic nature of the alkene partner. When unsymmetrical substituted 1,6-diynes 7 were used, the reaction with acyclic alkenes took place regio- and stereoselectively
1,6-二炔与烯烃的“正式”和标准RuII催化的[2 + 2 + 2]环加成反应以相对较高的收率得到了双环1,3-环己二烯。当使用末端1,6-二炔1时,根据烯烃配偶体的无环或环状性质,得到两个异构的双环1,3-环己二烯4或6。当使用不对称取代的1,6-二炔7时,与无环烯烃的反应在区域和立体选择性进行,得到双环1,3-环己二烯8。级联过程表现为“正式” RuII催化的[2 + 2 +2]环加法解释了这些结果。最初,发生Ru催化的1,6-二炔1和7与无环烯烃的线性偶联,生成3型开放1,3,5-三烯,在热分解6e(-)π电环化反应后,生成3最终的1,3-环己二烯4和8。