An efficient synthesis of 4-dimethoxyphosphonyl substituted pyrazoles and pyrazoline-5-ones

Abstract

2-Dimethoxyphosphonyl-1, 3-dicarbonyl compounds (1a-c) were used for the synthesis of 4-dimethoxyphosphonyl substituted pyrazoles (2a-e) and pyrazoline-5-ones (5a-c). Intermediate hydrazones (3b, c) were also isolated. 5a exists in the OH tautomeric form, whereas 5c-in the NH form. Tautomeric transition from the OH into the NH form was found for 5b at the melting point. © 1993, Taylor & Francis Group, LLC. All rights reserved.