US Patent 7973185 Process for the preparation of phenolic hydroxy-substituted compounds

The invention relates to a process for the preparation of a phenolic hydroxy-substituted compound of the general formula (I) by desalkylation of an alkyl aryl ether of the general formula (II) by treatment with a thiourea/aluminum chloride reagent pair, in said general formulae R1 stands for straight chain or branched C1-6 alkyl group; R2, R3 , R4 , R5, and R6 have the same or different meanings and stand for hydrogen or halogen atom, hydroxy, carboxy, nitro, oxo, C1-6 alkylcarbonyl, straight chain or branched alkyl or -alkoxy, or aryl group, or R2 and R3 together stand for a 5-7 membered ring or fused ring system; said 5-7 membered ring may be a partially saturated ring optionally substituted with an oxo group or can be an unsaturated ring; or said fused ring system may constitute with the first ring a steroid, preferably an estratriene derivative optionally substituted with an oxo or C1-6 alkylcarbonyloxy group in the 17 position.