n-butyllithium in tetrahydrofuran; hexane (Ar); soln. of n-BuLi in hexane was added dropwise to soln. of alkyne inTHF at -78°C; mixt. was stirred at -78°C for 30 min; Sn c ompd. was added; mixt. was stirred for 30 min and slowly warmed from -78°C to -30°C; extd. (ether/H2O); aq. phase washed (ether); combined org. phase dried (MgSO4); filtered; concd.;