Patent ID: 6225469
Filing Date: 2001-05-01
Classification: C07D

Abstract:
A process for the preparation of compounds of formula I ##STR9##including pharmaceutically acceptable salts, racemates, enantiomers, diastereoisomers and mixtures thereof in which:R.sub.1 represents H or one of the following groups: C.sub.1-6 alkyl, C.sub.1-6 alkoxy or C.sub.1-6 alkanoyl wherein each of the foregoing groups is optionally substituted by one or more of halo or cyano,; R.sub.2 and R.sub.3 independently represent H or one of the following groups: C.sub.1-6 alkyl, C.sub.1-6 alkoxy or C.sub.1-6 alkanoyl, C.sub.1-6 alkylthio, C.sub.1-6 alkylsulphinyl or C.sub.1-6 alkylsulphony wherein each of the foregoing groups is optionally substituted by one or more of halo or cyano;R.sub.4 and R.sub.5 independently represent H, C.sub.1-6 ralkyl or R.sub.4 and R.sub.5 combined together with the carbon atom to which they are attached represent C.sub.3-6 cycloalkylidene wherein each alkyl or cycloalkylidene is optionally substituted with one or more of halo, cyano or C.sub.1-6 alkyl; andR.sub.6, R.sub.6, and R.sub.8 independently represent H, halo, nitro, cyano or one of the following groups: C.sub.1-6 alkyl, C.sub.1-6 alkanoyl, C.sub.1-6 alkoxy, C.sub.2-6 alkoxycarbony, carboxy, C.sub.1-6 alkanoyloxy, C.sub.1-6 alkylthio, C.sub.1-6 alkylsulphinyl, C.sub.2-6 alkylsulphonyl, C.sub.1-6 alkylsulphonylamino, sulphamoyl, carbamoyl, C.sub.2-6 alkylcarbamoyl or C.sub.1-6 alkanoylamino wherein each of the foregoing groups is optionally substituted by one or more halo or cyano,; andany nitrogen atom is optionally substituted with one or more C.sub.1-6 alkyl; sulphonylamino, sulphamoyl, carbamoyl, C.sub.2-6 alkylcarbamoyl or C.sub.1-6 alkanoylamino;said process comprising the reaction involving an alcohol of formula II ##STR10##in which R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are as defined above, with a phenol of formula III ##STR11##in which R.sub.6, R.sub.7 and R.sub.8 are as defined above, in the presence of an inert diluent and at least one redox couple comprising an oxidizing agent and a reducing agent which is selected from a tri-substituted phosphine, arsine or stibine wherein the reducing agent becomes oxidized; whereina) a metal salt is added to form a complex or complexes with the oxidized reducing agent or agents produced in the process, andb) the resultant complex or complexes is/are separated from the desired product.