1: With isopropylmagnesium chloride in tert-butyl methyl ether T=0°C; 2: With sulfur dioxide in ethylene glycol dimethyl ether; tert-butyl methyl ether T=40°C; 1 h; 3: With hydrogenchloride; N-chloro-succinimide more than 3 stages;

hydrogenchloride; sodium hypochlorite; calcium chloride in dichloromethane; water T=-15 - -5°C;