1: 1,2-dihydrofuran With tert.-butyl lithium in tetrahydrofuran; pentane T=-60 - 0°C; 1 h; 2: tributyltin chloride in tetrahydrofuran; pentane T=-60 - 0°C; 1.5 h; 3: With water; ammonium chloride in tetrahydrofuran; pentane

tert.-butyl lithium; lithium chloride; bis(triphenylphosphine)palladium(II)-chloride in N,N,N',N',N'',N''-hexamethylphosphoric triamide; N,N-dimethyl-formamide

hexacarbonyl molybdenum; triethylamine in diethyl ether Irradiation (UV/VIS); N2-atmosphere; irradn. (20 min), alkynyl alcohol and Sn-compd. addn., stirring (18 h); evapn., chromy. (SiO2, pentane / Et2O / 1percent Et2NH);