1H-imidazole in N,N-dimethyl-formamide T=25°C;

2,6-dimethylpyridine in dichloromethane T=-78°C; 1.5 h;

in dimethyl sulfoxide T=0°C;

1: 94.6 percent / 4-(dimethylamino)pyridine / CH2Cl2 / 16 h / Ambient temperature 2: 68.5 percent / dimethylsulfoxide / 0 °C View Scheme

Grubb's 2nd generation catalyst; copper(II) sulfate in water; tert-butyl alcohol T=80°C; 0.5 h; Microwave irradiation; optical yield given as percent de;

1: bis[N(C2H5)2]-bis{[N-((2,6-iPr)phenyl)]benzamidate}titanium / benzene / 24 h / 65 °C 2: silica gel / benzene View Scheme

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.; Aq. phase was extd. (ether). The org. exts. were washed (satd. aq. NH4Cl) and dried (MgSO4). Removal of the solvent; column chromy. (silica gel) followed by distillation. (E)-1-trimethylstannyl-1-alkene was not isolated, detected by gas-liq. chromy..;

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

1: 99 percent / n-BuLi / tetrahydrofuran / 4 h / -78 - 20 °C 2: 99 percent / pyridinium p-toluene sulfonate / CH2Cl2 3: 95 percent / TBAF / tetrahydrofuran / 0 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 1.5 h / -5 °C 1.2: 90 percent / hexamethylphosphoric acid triamide; tetrahydrofuran; hexane / 10 h / 20 °C 2.1: HF / acetonitrile / 0.5 h / 20 °C View Scheme