Regioselective chlorination of 4- and 5-methyl-2,2,2-trichlorobenzo[d]-1,3,2-dioxaphospholes

The reactions of 4- and 5-methyl-2,2,2-trichlorobenzo[d]-1,3,2-dioxaphospholes with molecular chlorine in an 1:1 ratio occur selectively to give 4-methyl-2,2,2,5-tetrachloro- and 5-methyl-2,2,2,6-tetrachlorobenzo[d]-1,3,2-dioxaphospholes, which undergo hydrolysis to 4-chloro-3-methyl- and 4-chloro-5-methyl-1,2-dihydroxybenzenes, respectively.