iodine in dichloromethane T=20°C; 0.5 h;

ammonium chloride in tetrahydrofuran; methanol; water To a stirred soln. of Me3SnCu*Me2S in THF (Ar, -78°C) was added sequentially a THF soln. of the 1-alkyne and CH3OH. The mixt. was stirred(10 min) and then at -63°C (12 h). Satd. aq. NH4Cl and ether were added; allowed to warm to room temp.; Extn. of the aq. phase (ether). The org. exts. were washed (satd. aq. NH4Cl) and dried (MgSO4). Removal of the solvent; chromy. (silica gel); distn. of the less polar oil gave 4-chloro-2-trimethylstannyl-1-butene; preparative chromy. gave minor product.;

methanol in tetrahydrofuran molar ratio Sn:alkyne:MeOH=1:2:60; chromy. (SiO2, light petroleum);

methyllithium in tetrahydrofuran react. at -78°C;

Multistep reaction;