n-butyllithium in tetrahydrofuran; hexane (Ar); addn. of hexane soln. of butyllithium to soln. of thiophene deriv.in dry THF at -78°C, stirring for 80 min with warming to -10.deg ree.C, addn. of tin compd. at -78°C, warming to room temp. over 2h, stirring for 19 h; addn. into water, extn. (diethyl ether), drying over Na2SO4, evapn. in vac., NMR and MS;