Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Am Chem Soc. 2013 Oct 2;135(39):14508-11. doi: 10.1021/ja4068468. Epub 2013 Sep 19.
A density functional theory (DFT) study was performed to elucidate the mechanism of the Ni-catalyzed [3 + 2 + 2] cyclization reaction of cyclopropylideneacetate with two alkynes. A systematic search showed that the nature of the alkynes determines the choice between two reaction pathways and hence the regioselectivity. Strongly electron-deficient acetylenes preferentially afford 2,5-disubstituted products via nickelacyclopentadienes generated by [2 + 2] cocyclization, whereas normal alkynes afford 3,4- or 3,5-products via an unprecedented pathway involving a [3 + 2] nickelacycle intermediate.
采用密度泛函理论（DFT）研究了镍催化的环丙叉乙酸酯与两个炔烃的[3+2+2]环化反应的机理。系统搜索表明，炔烃的性质决定了两条反应途径的选择，从而决定了区域选择性。强缺电子炔烃优先通过[2+2]共环化生成的镍环戊二烯来得到 2,5-二取代产物，而正常炔烃则通过一条前所未有的途径得到 3,4-或 3,5-产物，该途径涉及[3+2]镍环中间体。
