in diethyl ether; hexane byproducts: cuprous acetate; addn. from a syringe of 2-lithiothiophene soln. to a stirred suspn. of CuI in Et2O, -70°C, (colour change from grey to white then to olive), 2 h, addn. of a soln. of (C4H9)2SnClOAc, stirring 18 h; filtered (Cu(OAc)2), the filtrate vac. concd., elem. anal.;