Patent ID: 6703509
Filing Date: 2004-03-09
Classification: C07D

Abstract:
A process for the preparation of a 5-aryinicotinaldehyde of formula I in whichA is a phenyl radical or naphthyl radical, each of which is unsubstituted, monosubstituted or polysubstituted by R, F, Cl, Br, I, â€”CN, â€”NO2, â€”CF3, â€”OCF3, â€”OCHF2, â€”OCF2CF3 or â€”OH and in which or more CH groups is optionally replaced by N, and R is H, a straight-chain or branched alkyl radical having 1 to 15 carbon atoms which is monosubstituted by â€”CF3 or at least monosubstituted by fluorine, where, in addition, one more CH2 groups is optionally independently replaced by â€”Sâ€”, â€”Oâ€”, â€”Oâ€”COâ€”, â€”COâ€”Oâ€” or â€”CH&boxH;CHâ€” in such a way that heteroatoms are not directly adjacent, said process comprising reduction of a corresponding 5-aryinicotinic acid by catalytic hydrogenation in the presence of carboxylic anhydrides and a palladium/ligand complex, wherein molar ratio between palladium and ligand is from 1:5 to 1:15 in the case of monodentate ligands and from 1:2.5 to 1:7.5 in the case of bidentate ligands.