Catalytic hydrogenation of substituted cyanopyridines and process for preparing substituted pyridylmethylbenzamides

A process for preparation of one or more substituted pyridylmethylbenzamides of formula (I)

• wherein
• p is an integer equal to 1, 2, 3 or 4,
• q is an integer equal to 1, 2, 3 or 4,
• each substituent X is, independently of the others, hydrogen, halogen, C1-C4 alkyl or C1-C4 haloalkyl with the proviso that the at least one X is halogen,
• Y is halogen,
• comprising
• in a step (B1) hydrogenating a substituted cyanopyridyl derivative according to formula (II)
• wherein p and X are defined as above,
• in the presence of a metal catalyst, a catalyst modifier and an acid, wherein an amount of the catalyst modifier is in a range from about 0.0000001 equivalents to about 10 equivalents with respect to the amount of cyanopyridyl derivative according to formula (II), to give a compound of formula (III) or corresponding salts thereof
• wherein p and X are defined as above,
• and further comprising in a step (B2) reacting the compound of formula (III) or one or more corresponding salts thereof,
• wherein p is an integer equal to 1, 2, 3 or 4;
• each substituent X is, independent of the others, halogen, C1-C4 alkyl or C1-C4 haloalkyl;
• in a suitable solvent in the presence of a suitable base with a compound of formula (IV)
• wherein
• q is an integer equal to 1, 2, 3 or 4,
• Y is halogen and
• L1 is a leaving group,
• to give one or more substituted pyridylmethylbenzamids of formula (I);
• wherein an amount of dehalogenated side-products is less than or equal to 1% of the one or more substituted pyridylmethylbenzamides of formula (I) produced by the process;
• and
• wherein the catalyst modifier is selected from the group consisting of n-tetrabutylammonium iodide, n-tetramethylammonium bromide (TMAB), n-tetraethylammonium bromide, n-tetrabutylammoniumbromide (TBAB), n-tetramethylammonium chloride, n-tetraethylammonium chloride, and n-tetrabutylammoniumchloride.