Synthesis of 1-(2-Fluorophenyl)pyrazoles by 1,3-Dipolar Cycloaddition of the Corresponding Sydnones

Abstract

3-Arylsydnones bearing fluorine and bromine atoms on the benzene ring were synthesized from N-nitroso-2-fluorophenylglycines and characterized by NMR spectroscopy. These were employed further in synthesis of the corresponding 1-(2-fluorophenyl)pyrazoles by 1,3-dipolar cycloaddition reaction with dimethyl acetylenedicarboxylate (DMAD) as activated dipolarophile. The sydnones as reaction intermediates were characterized by single crystal X-ray diffraction analysis showing interesting features such as halogen bonding as an important interaction in modeling the crystal structure.

Huisgen 3 + n Dipolar Cycloaddition Reactions: An Accessible and Useful Tool in Modern Organic and Heterocycle Synthesis

“…This Special Issue (SI) focuses on Huisgen 3 + n dipolar cycloaddition reactions as a useful and powerful tool in the synthesis and chemistry of new heterocycle derivatives. The SI provides an update of relevant and important original contributions [1,2,[4][5][6][7][8] and reviews [3,9] pertaining to these reactions, which have brought about significant advances in the development of the field of heterocycle derivatives.…”

“…The next original contribution is related to the synthesis of substituted pyrazoles via a [3 + 2] dipolar cycloaddition reaction cycloaddition of sydnones with acetylenedicarboxylate (DMAD) as a dipolarophile [6]. The authors synthetise new polyhalogenated N-arylglycines, 3-arylsydnones, and 1-arylpyrazoles containing a fluorine atom within their molecules.…”