Chlorinations of derivatives of 2,2,2-trichlorobenzo-1,3,2-dioxaphospholes

By ³¹P, ¹³C, ¹³C-{¹H}, and ¹H NMR spectroscopy the chlorination of 4-and 5-methyl-2,2,2-trichlorobenzo-1,3,2-dioxaphosphols was shown to provide in quantitative yield 4-methyl-2,2,2,5-tetrachloroand 6-methyl-2,2,2,5-tetrachlorobenzo-1,3,2-dioxaphosphols. Their hydrolysis led to the formation of difficultly available 4-methyl-5-chloro-and 3-methyl-4-chloro-1,2-dihydroxybenzenes. The structure of the latter compound was established by XRD analysis. The 5-methyl-2-chlorobenzo-1,3,2-dioxaphosphol treated with excess chlorine was converted in succession into 5-methyl-2,3,4,5,6,6-hexachlorocyclohex-1-en-3-yl dichlorophosphate and 5-methyl-1,2,4,4,5,6-hexachlorocyclohex-1-en-3-yl dichlorophosphate. The hydrolysis resulted in 5-methyl-2,3,4,5,6,6-hexachlorocyclohex-2-en-1-yl dihydrophosphate. The configuration of three chiral carbon atoms in the latter was established by XRD study. In the course of the chlorination the aromaticity of the ortho-phenylene fragment was distorted and 3,3-sigmatropic shift of the dichlorophosphoryl group occurred. The reaction with chlorine of 5-tert-butyl-2,2,2-trichlorobenzo-1,3,2-dioxaphosphol and 2,2,2-trichloro-benzo-1,3,2-dioxaphosphol was not selective: The reaction product obtained in excess chlorine transformed on hydrolysis into tetrachloropyrocatechol. Its solvates with water and dioxane were studies by XRD analysis.