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

Denisa Dumitrescu; Sergiu Shova; Constantin Draghici; Marcel Mirel Popa; Florea Dumitrascu

doi:10.3390/molecules26123693

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

Molecules. 2021 Jun 17;26(12):3693. doi: 10.3390/molecules26123693.

Authors

Denisa Dumitrescu¹, Sergiu Shova^{2

3}, Constantin Draghici⁴, Marcel Mirel Popa⁴, Florea Dumitrascu⁴

Affiliations

¹ Faculty of Pharmacy, Ovidius University Constanta, Str. Cpt. Av. Al. Serbanescu, Campus Corp C, 900470 Constanta, Romania.
² CEEC Institute, Ningbo University of Technology, No. 201 Fenghua Road, Ningbo 315021, China.
³ Department of Inorganic Polymers, "Petru Poni" Institute for Macromolecular Chemistry, Romanian Academy, Aleea Grigore Ghica Voda, 41A, 700487 Iasi, Romania.
⁴ Center of Organic Chemistry ''C. D. Nenitzescu'', Roumanian Academy, Spl Independentei 202B, 060023 Bucharest, Romania.

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.

Keywords: 1,3-dipolar cycloaddition; X-ray diffraction; halogen bonding; pyrazole; sydnone.