1: isopropyl bromide With magnesium in diethyl ether Inert atmosphere; 2: coumarin With copper(I) bromide dimethylsulfide complex; triphenylphosphine in diethyl ether; tert-butyl methyl ether T=-40°C; Inert atmosphere; 3: With hydrogenchloride in diethyl ether; tert-butyl methyl ether Inert atmosphere; enantioselective reaction;