Patent ID: 6844436

Claim:
A method for preparing pyrazolopyrimidinone derivatives of formula 1, as represented in the following scheme 1, comprising the following steps of: a) chlorosulfonating a pyrazolamide compound of formula 2 to obtain a chlorosulfonated compound of formula 3; b) reacting the chlorosulfonated compound of formula 3 with a primary amine to obtain a sulfonamide compound of formula 4; and, c) performing an intramolecular cyclization of the sulfonamide compound of formula 4 to produce the compound of formula 1, wherein the step b) and c) are performed in situ in alcohol by adding a base to the reaction mixture without workup after the step b) is completed: wherein R 1 represents hydrogen; C 1 -C 6 alkyl; C 1 -C 3 alkyl fluoride; or C 3 -C 6 cycloalkyl, R 2 represents hydrogen; substituted or unsubstituted C 2 -C 6 alkyl; C 1 -C 3 alkyl fluoride; or C 3 -C 6 cycloalkyl, R 3 represents substituted or unsubstituted C 1 -C 6 alkyl; C 1 -C 6 alkyl fluoride; C 3 -C 6 cycloalkyl; C 3 -C 6 alkenyl; or C 3 -C 6 alkynyl, and R 4 represents substituted or unsubstituted C 1 -C 10 alkyl; substituted or unsubstituted C 1 -C 9 alkenyl; substituted or unsubstituted C 3 -C 6 cycloalkyl; substituted or unsubstituted bezene; or substituted or unsubstituted heterocycle selected from the group consisting of pyridine, isoxazole, thiazole, pyrimidine, indan, benzthiazole, pyrazole, thiadiazol, oxazole, piperidine, morphorine, imidazole, pyrrolidine, thienyl, triazole, pyrrole and furyl, in which, substituents usable for R 2 , R 3 and R 4 comprises C 1 -C 10 alkyl; C 3 -C 6 cycloalkyl; halogen; C 1 -C 6 alkyl fluoride; C 1 -C 10 alkyloxy; substituted or unsubstituted bezene; or substituted or unsubstituted heterocycle selected from the group consisting of pyridine, isoxazole, thiazole, pyrimidine, indan, benzthiazole, pyrazole, thiadiazole, oxazole, piperidine, morphorine, imidazole, pyrrolidine, thienyl, triazole, pyrrole, and furyl.