New pyrazoles by 1, 3-dipolar cycloaddition reactions between sydnones and activated alkynes

F DUMITRAŞCU, C DRĂGHICI, D Vuluga…

Index: Dumitrascu, Florea; Draghici, Constantin; Vuluga, Daniela; Caproiu, Miron Teodor Revue Roumaine de Chimie, 2006 , vol. 51, # 4 p. 255 - 260

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Citation Number: 6

Abstract

The 3-(2, 4-dimethylphenyl) sydnone (8a) was halogenated at the 4-position giving 4- halogenosydnones 8b-d. The 1, 3-dipolar cycloaddition reactions of sydnones 8 with symmetrical and non-symmetrical acetylenic esters afforded pyrazoles 9a-g, 10a, b and 11, respectively. The variation of the 13C-NMR chemical shifts for the endocyclic carbons in the sydnone and pyrazole ring correlated with the nature of the halogen atom was determined.