halogenated indeno[1,2-c]chromene derivatives is described. Treatment of aryldiynes 1 with one equivalent of iodine gave iodinated indeno[1,2-c]chromenes 3 in good chemical yields. When two equivalents of iodine were employed into the reaction mixture, dimer 9 was obtained as the major products. On the other hand, reaction of two equivalents of CuBr2 with compounds 1 gave the brominated indeno[1,2-c]chromenes
描述了芳基二炔的卤素介导的环化反应以产生卤化的茚并[1,2- c ]亚甲基衍生物。用一当量的碘处理芳基二炔1可以得到良好的化学收率的碘化茚并[1,2- c ]苯二酮3。当将两当量的碘用于反应混合物中时,获得二聚体9作为主要产物。在另一方面,溴化亚铜的两个当量的反应2用化合物1,得到溴化茚并[1,2- c ^ ]苯并吡喃4。为了了解取代基如何影响环化途径,对含甲氧基,羧基,氨基和硫化物取代基的分子进行了碘介导的环化反应的DFT计算。
Reactivity Switch Enabled by Counterion: Highly Chemoselective Dimerization and Hydration of Terminal Alkynes
作者:Caixia Xu、Weiyuan Du、Yi Zeng、Bin Dai、Hao Guo
DOI:10.1021/ol403684a
日期:2014.2.7
A counterion-controlled reactivity tuning in Pd-catalyzed highly chemoselective and regioselective dimerization and hydration of terminalalkynes is reported. The use of acetate as counterion favors the formation of an alkenyl alkynyl palladium intermediate which forms hitherto less reported 1,3-diaryl-substituted conjugated enynes after reductive elimination. Using chloride, which is a better leaving