in dimethyl sulfoxide T=0 - 20°C;

1: acetylene With n-butyllithium in tetrahydrofuran; hexane T=-78°C; Inert atmosphere; 2: (S)-(+)-4-methyl-2,2-dioxo-1,3,2-dioxathiolane in tetrahydrofuran T=-78 - 20°C; 3: With sulfuric acid; water in tetrahydrofuran 0.5 h;

ethylenediamine in dimethyl sulfoxide Ambient temperature;

tetrabutyl ammonium fluoride in tetrahydrofuran 0.25 h; Ambient temperature;

boron trifluoride diethyl etherate

lithium 1.) liq. NH3, -78 deg C, 2.) DMSO, a) 15 deg C, 30 min, b) RT, 2.0 h; Yield given. Multistep reaction;