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.
![2-[(2,3-dimethylphenyl)amino]acetic acid Structure](https://image.chemsrc.com/caspic/214/83442-59-5.png)