Process for preparing pyridine derivatives

Claim 1

A process for preparing a compound of formula I ##STR5## or a pharmaceutically acceptable acid addition salt thereof, wherein Z is --CONH 2 , --CSNH 2 or --CN; R 1 , r 2 and R 6 are independently hydrogen, trifluoromethyl, alkyl of 1 to 6 carbon atoms, phenylalkyl of 7 to 12 carbon atoms or phenyl, or R 1 and R 2 taken together represent an R 7 substituted alkylene chain, said alkylene chain consisting of 3 to 5 carbon atoms, inclusive; R 7 is hydrogen, alkyl of 1 to 6 carbon atoms, gem-di-n-alkyl in which each alkyl group has 1 to 6 carbon atoms, phenylalkyl of 7 to 12 carbon atoms or phenyl; m is one of the integers 1, 2 or 3; with the proviso that when R 1 and R 2 or R 2 and R 6 are both alkyl, they are normal or secondary alkyl; which process comprises the steps of treating a compound of formula II ##STR6## wherein R 1 , R 2 , R 6 , R 7 and m are defined above and M is sodium, potassium, lithium, MgCl, MgBr or MgI; with a compound of the formula: R.sub.X Si(NCY).sub.4-X wherein each R group is independently alkyl of 1 to 6 carbon atoms, phenyl or aralkyl of 7-12 carbon atoms; Y is oxygen or sulfur; and X is an integer from 0 to 3, inclusive followed by hydrolysis or alcoholysis of the product, with the proviso that when Z is --CN the molar ratio of R X Si(NCY) 4-X to compound II is at least 2:1, X is 3 and Y is sulfur, and with the additional proviso that when Z is --CONH 2 or --CSNH 2 , the molar ratio of R X Si(NCY) 4-X to compound II is less than 4:1.