METHOD OF PREPARATION OF SILDENAFIL

摘要

A method of preparation of sildenafil, i.e. 5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl) phenyl]-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazole[4,3-d]pyrimidin-7-one of formula (I) comprises the reaction of 2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)benzaldehyde of formula (II) and 4-amino-1-methyl-3-n-propylpyrazole-5-carboxyamide of formula (III). The starting compound and the intermediate compound useful in the said method are new.