acetyl chloride; titanium tetrachloride in dichloromethane dry CH2Cl2, -78°C warming to -35°C, ratio of educts: stannane:acid chloride:TiCl4 = 2:1:2; chromy. (silica gel, petroleum/ethyl acetate);

titanium tetrachloride in dichloromethane -78 to -35 deg C;

titanium tetrachloride in dichloromethane -78 to -35 deg C;