Patent ID: 6953860

Claim:
A process for preparing a compound of the formula I wherein R 1 , R 2 , R 3 and R 4 are the same or different and are individually selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, amino, acetamido, phenyl, halo, hydroxy, lower alkylsulfonyl, lower alkylthio, nitro, trifluoromethyl, omega-trifluoromethyl lower alkoxy, or where R 1 , R 2 or R 3 , R 4 taken together with the phenyl group to which they are attached, form a naphthyl or substituted naphthyl group; comprising reacting a compound of formula III wherein R 3 and R 4 are as described above, with a compound of formula IV wherein R 1 and R 2 are as decribed above, to form a compound of formula V which is not isolated wherein R 1 , R 2 and R 4 are as decribed above, reacting the reaction mixture of compound of formula V with an alcohol to form a reaction mixture comprising the corresponding ester of formula VI wherein R is lower alkyl, R 1 , R 2 and R 4 are as decribed above, and without isolating the ester of formula VI reacting the reaction mixture of ester of formula VI with N-methylhydroxylamine hydrochoride and a base to form the compound of formula I.