Patent ID: 6770781
Filing Date: 2004-08-03
Classification: C07C

Abstract:
A process for the preparation of meta or para-substituted &agr;-arylalkanoic acids of formula (I): whereinR is hydrogen; C1-C6 alkyl; R1 is hydrogen, straight or branched C1-C6 alkyl, phenyl, p-nitrophenyl, a cation of an alkali or alkaline-earth metal cation or of a pharmaceutically acceptable ammonium salt; A is C1-C4 alkyl, aryl, aryloxy, arylcarbonyl, 2-, 3- or 4-pyridocarbonyl, aryl optionally substituted with one or more alkyl, hydroxy, amino, cyano, nitro, alkoxy, haloalkyl, haloalkoxy; A is at the meta or para positions; which process comprises the following steps: a) reaction of compounds of formula (II) in which P is straight or branched C1-C6 alkyl, phenyl, p-nitrophenyl, with a thiocarbonyl halide to give compounds of formula (III) whereinRa and Rb are C1-C6 alkyl, b) thermal rearrangement of compound (III) to give (IIIb) c) catalytic hydrogenation of (IIIb) to give (IIIc) d) hydrolysis of (IIIc) and optional subsequent reesterfication or salification to give (I).