Transition Metal-Catalyzed Cascade Cyclization of Aryldiynes to Halogenated Benzo[b]naphtho[2,1-d]thiophene Derivatives

Treatment of 2-(2-(2-(2-substituted ethynyl)phenyl)ethynyl)thioanisoles (1) with 5 mol % of Ph3PAuCl/AgSbF6 and 2 equiv of NIS at refluxing CH2Cl2 gave iodo-substituted benzo[b]naphtho[2,1-d]thiophene (6) in good yields. Chloro- and bromo-substituted benzo [b]naphtho [2,1-d] thiophene derivatives (8 and 9) were also generated by treating compound 1 with 5 mol % of PdX2 and 3 equiv of CuX2 at refluxing THF.