PREPARATION OF 5-2-ETHOXY-5-(4-METHYLPIPERAZIN-1-YLSULPHONYL)PHENYL-1-METHYL -3-(N-PROPYL)-1,6-DIHYDRO-7H-PYRAZOLO4,3-DPYRIMIDIN-7-ONE(SIL DENAFIL) AND INTERMEDIATES DENA 5-2-ETHOXY-5-(4-METHYLPIPERAZIN-1-YLSULPHONYL)PHENYL-1-METHYL -3-(N- PROPYL)-1,6-DIHYDRO-7H-PYRAZOLO4,3-DPYRIMIDIN-7-ONE(SLIDENAFI L);INT ERMEDIATES

摘要

A process for the preparation of a compound of formula (I): CHEM also knows as sildenafil which comprises cyclisation of a compound of formula (II): CHEM