David J. DalePeter J. DunnClare GolightlyMichael L. HughesPhilip C. LevettAndrew K. Pearce2012-11-092025-02-172012-11-092012-11-09https://dl.ftveti.edu.et/handle/123456789/3964This 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 pyrazolo[4,3-d]- pyrimidines 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 discussedThis 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 pyrazolo[4,3-d]- pyrimidines 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 discussedenThe Chemical Development of the Commercial Route to Sildenafil: A Case HistoryArticle