Dichotomous reactivity of PCl5 and PBr5 toward cyclic ketones: A one-step preparation of 1,1,2-trichlorocycloalkanes
Small-ring cyclic ketones react with excess PCl5 in CCl4 (reflux, 1-3 d) to give the corresponding 1,1,2-trichlorocycloalkanes, but react with PBr5 to give ketones brominated in the α-positions.