1: trimethylsilylacetylene With n-butyllithium in hexane; toluene T=0°C; 0.5 h; Inert atmosphere; 2: ethylaluminum dichloride in hexane; toluene T=0°C; 0.5 h; Inert atmosphere; 3: 4'-benzenesulfonyl-3',5'-bis-O-(tert-butyldimethylsilyl)thymidine in hexane; toluene T=0 - 20°C; 1 h; Inert atmosphere; optical yield given as percent de;

in hexane; dichloromethane T=0 - 20°C; 1 h; optical yield given as percent de;