Browsing by Author "Michael L. Hughes"

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    The Chemical Development of the Commercial Route to Sildenafil: A Case History
    (2012-11-21) David J. Dale; Peter J. Dunn; Clare Golightly; Michael L. Hughes; Philip C. Levett
    The Chemical Development of the Commercial Route to Sildenafil: A Case History David J. Dale, Peter
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    The Chemical Development of the Commercial Route to Sildenafil: A Case History
    (2012-11-09) David J. Dale; Peter J. Dunn; Clare Golightly; Michael L. Hughes; Philip C. Levett; Andrew K. Pearce
    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 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 discussed