1: With AlCl3, aluminium chloride; sodium bromide in acetonitrile; tert-butyl alcohol T=20°C; Inert atmosphereReflux; 2: With water in acetonitrile; tert-butyl alcohol Inert atmosphere; stereoselective reaction;

CeF3; trimethylsilyl bromide in acetonitrile 42 h; Ambient temperature; Yield given. Yields of byproduct given;