PROCESS FOR PREPARING 5-(4-ALKYLPIPERAZINYLSULFONYLPHENYL)-PYRAZOLO[4,3-D]PYRIMIDIN-7-ONE DERIVATIVES

摘要

PURPOSE: A method for preparing 5-(4-alkylpiperazinylsulfonyl phenyl)-pyrazolo[4,3-d]pyrimidine-7-one compounds is provided to obtain a large amount of the compounds. CONSTITUTION: A method for preparing 5-(4-alkylpiperazinyl sulfonylphenyl)-pyrazolo[4,3-d]pyrimidine-7-one compound of chemical formula 1 comprises a step of oxidation cyclization of a benzaldehyde compound of chemical formula 2 with an amine compound of chemical formula 3 under the presence of sodium bisulfite(NaHSO_3), sodium methasulfite(Na_2S_2O_5), lead acetate, or oxone. The compound of chemical formula 1 is sildenafil.