n-butyllithium in tetrahydrofuran; diethyl ether; hexane under Ar atm. to soln. 1-methylimidazole in THF at -15°C soln. n-BuLi in hexane was added and stirred at -10°C for 2 h, soln. Bu3SnCl in ether was added over 1.5 h and allowed to warm to room temp.; soln. was concd., residue was distilled at 0.2 mm and 160-180°C;