Key points are not available for this paper at this time.
This paper is a case history of the chemical development of sildenafil which covers various aspects of work in chemical development namely: route selection, scale-up issues, the development of an efficient synthesis with high throughput, process safety, and environmental issues. Interesting chemical points include improved methods of preparing pyrazolo4,3-dpyrimidines and the unusual isolation of an intermediate as its double salt (10). The potential dangers of nitrating pyrazole-5-carboxylic acids which are activated to a decarboxylation reaction are discussed.
Dale et al. (Fri,) studied this question.