SnCl₂/EtOH-Mediated Synthesis of Novel 4-Ethoxy- and 4-Chloroindazoles Bearing Sulfonamide Moieties

Abstract

The treatment of N-alkyl-5-nitroindazole with stannous chloride in ethanol, aftercoupling of the obtained amines with arylsulfonyl chloride in pyridine, gave the new 4-ethoxy- and 4-chloroindazoles bearing sulfonamide in moderate to good yields. Chlorination and ethoxylation of indazole were observed during the reduction of the nitro group with anhydrous SnCl₂ in ethanol. The influence of the N-alkylation in N-1 and N-2 position of 5-nitroindazole on the reduction was investigated. The presence ofethoxy group and chlorine atom at position C-4 of indazole was confirmed by x-ray diffraction analysis of compounds 7a and 8a.

Graphical Abstract

Keywords:

• Arylsulfonyl chloride
• N-alkyl-5-nitroindazoles
• N-(4-chloroindazol-5-yl)-arylsulfonamides
• N-(4-ethoxyindazol-5-yl)-arylsulfonamides
• reduction
• stannous chloride

ACKNOWLEDGMENTS

We acknowledge the National Centre for Scientific and Technical Research (CNRST), Rabat, for providing the NMR and x-ray crystallography of our compounds.

SUPPLEMENTAL MATERIAL

Full characterization data, ¹H and ¹³C NMR spectra, and x-ray crystallographic materials for this article can be accessed on the publisher’s website.