Cupric halide mediated cyclization reactions: Synthesis of 3-haloindoles and 3-halobenzo[c]thiophenes

ORGN 125

Ming-Jung Wu, mijuwu@kmu.edu.tw, Wen-Der Lu, and Zhi-Chao Chuang. Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
Cupric chloride and bromide are found to be excellent halocyclization agents for 2-alkynylthioanisoles and 2-alkynylanilines. Thus, treatment of 2-alkynylthioanisoles with two equivalents of CuX2 (X = Cl or Br) under refluxing acetonitrile for 2-3 hours gave 3-halobenzo[c]thiophenes in good to excellent yields. On the other hand, N,N-dimethyl-2-alkynylanilines gave 3-haloindoles under similar reaction conditions.