A small molecule library of alkyl, sulfone, and carboxamide functionalized pyrazoles and isoxazoles has been developed via a rapid sequential condensation of various alpha-acylketene dithioacetals (1a-o) with hydrazine hydrate or hydroxylamine hydrochloride, followed by oxidation of sulfide to sulfone using water as the reaction medium. An efficient and safe oxidation of sulfides (4/5a-o) to the corresponding sulfones (6/7a-o) using sodium per borate system in aqueous medium is reported. The concise and two step synthesis of trisubstituted pyrazoles and isoxazoles was investigated under variety of reaction condition. The newly developed methodology has the advantage of excellent yield and chemical purity with short reaction time using water as a solvent.

A solution-phase library of the title compounds (V) and (VIII) with methyl, sulfone and carboxamide moieties is prepared by a two-step synthesis starting from (IV) using water as a green solvent. -(SAVANT, M. M.; PANSURIYA, A. M.; BHUVA, C. V.; KAPURIYA, N.; PATEL, A. S.; AUDICHYA, V. B.; PIPALIYA, P. V.; NALIAPARA*, Y. T.; J.

The synthesis of novel 3‐(4,5‐dichloro‐2‐fluorophenyl)‐1‐phenyl‐4‐(3‐phenylisoxazol‐5‐yl)‐1H‐pyrazole(7a–p) has been achieved via [3 + 2] heteroannulation reaction 3‐(3‐[4,5‐dichloro‐2‐fluorophenyl]‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐1‐phenylprop‐2‐en‐1‐one(6a–p) and hydroxylamine hydro chloride using cupric acetate as homogenous precatalyst. Pyrazole derivatives were prepared by using etidronic acid as catalyst followed by Vilsmeier‐Haack reaction. An efficient green synthesis of isoxazole derivatives bearing pyrazole ring has been demonstrated with excellent yields. Structures of novel isoxazole derivatives were confirmed by elemental analysis and 1H NMR, 13C NMR, Mass, IR spectral studies.