Process for the preparation of sildenafil and intermediates...

Details Process for the preparation of sildenafil and intermediates... Process for the preparation of sildenafil and intermediates...

2006-12-21

2011-12-06

Murray, Jeffrey (Department: 1624)

Organic compounds -- part of the class 532-570 series

Organic compounds

Pteroyl per se or having -c-, wherein x is chalcogen, bonded...

Reexamination Certificate

active

08071765

ABSTRACT:
The present invention discloses a process for preparing sildenafil and its intermediates having the structures outlined below:In particular, the present invention provides a process for preparing the compound of formula (I) and its intermediates, i.e. the compounds of formula (I), (II), (III) and (IV). The compound of formula (I) is obtained from the compound of formula (II); the compound (II) is obtained from the compound of formula (III) and methylpiperazine; the compound (III) is obtained by treating the compound of formula (IV) with chlorosulfonic acid; the compound (IV) is obtained though treating the compound of formula (V) in the presence of at least one selected from POX3, PX3, PX5and their mixtures in any ratio. The process for preparing the compound of formula (I) according to the present invention reduces the side reactions in the processes of the prior art. These improvements lead to higher yields and a better industrial applicability with easier controlling of the reaction.

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Xu, Baofeng et al., Huaxue Yanjiu Yu Yingyong, Oct. 2002, 14(5): 605-607, ISSN: 1004-1656.
Khalid M. Khan, et al. A facile and improved synthesis of sildenafil (Viagra) analogs through solid support microwave irradiation possessing tyrosinase inhibitory potential, their conformational analysis and molecular dynamics simulation studies. Molecular Diversity (2005), 9(1-3): 15-26, ISSN: 1381-1991.
Baxendale et al., “Polymer-Supported Reagents for Multi-Step Organic Synthesis: Application to the Synthesis of Sildenafil”, Bioorganic & Medicinal Chemistry Letters 10 (2000) 1983-1986, 4 pages.

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