247582-73-6Relevant articles and documents
The process development of a scaleable route to the PDE5 inhibitor UK-357,903
Dale, David J.,Draper, John,Dunn, Peter J.,Hughes, Michael L.,Hussain, Farhat,Levett, Philip C.,Ward, Gordon B.,Wood, Albert S.
, p. 767 - 772 (2002)
A case history is outlined for the development of a scaleable route to the drug candidate UK-357,903. Despite the partial structural similarities to those of sildenafil (Viagra), the introduction of the central pyridine moiety within UK-357,903 had a significant impact on the commercial process. In particular, the triply activated 2-alkoxypyridyl moiety of UK-357,903 is much more susceptible to nucleophilic attack than the 2-ethoxyphenyl moiety of sildenafil, necessitating the development of new chemistry. Particular items of note are (i) the new six-step route to the advanced 2-ethoxy-5-(4-ethylpiperazinylsulfonyl)nicotinic acid intermediate and the subsequent telescoping to a two-pot process, (ii) the telescoping of the two steps from N-[3-carbamoyl-5-ethyl-1-(2-pyridylmethyl)-1H-pyrazol-4-yl]-2-ethoxy-5- (4-ethyl-1-piperazinylsulfonyl)nicotin-amide to UK-357,903 to a single step, with the additional use of a hydroxide trapping agent to give an ambient pressure process yielding clinical quality product, and (iii) the introduction of process modifications to allow for the use of teratogenic 2-methoxyethanol, as both reagent and solvent, in the penultimate process step.
Novel process for the preparation of pyrazolopyrimidinones
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, (2008/06/13)
There is provided a process for the production a compound of general formula I: wherein A, R1, R2, R3 and R4 have meanings given in the description, which process comprises the reaction of a compound of formula II, wherein Rx is a group substitutable by an aminopyrazole, with a compound of general formula III
Crystalline therapeutic agent
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, (2008/06/13)
A polymorph of 1-{6-ethoxy-5-[3-ethyl-6,7-dihydro-2-(2-methoxyethyl)-7-oxo-2H-pyrazolo[4,3-d]pyrimidin-5-yl]-3-pyridylsulfonyl}-4-ethylpiperazine.