5-Isobutyl-4-phenylsulfonyl-1H-pyrazol-3(2H)-one

The title compound, C13H16N2O3S, consists of two crystallographically independent molecules with similar geometries and exists in a keto form, the C=O bond lengths being 1.267 (2) and 1.254 (2) Å. In both molecules, the pyrazole rings are approximately planar, with maximum deviations of 0.017 (2) and 0.010 (2) Å, and the dihedral angles between the pyrazole and phenyl rings are 83.63 (11) and 70.07 (12)°. In one molecule, an intramolecular C—H⋯O hydrogen bond with an S(6) ring motif is observed. In the crystal, intermolecular N—H⋯O and C—H⋯O hydrogen bonds link the molecules into two-dimensional networks parallel to the ab plane.

The title compound, C 13 H 16 N 2 O 3 S, consists of two crystallographically independent molecules with similar geometries and exists in a keto form, the C O bond lengths being 1.267 (2) and 1.254 (2) Å . In both molecules, the pyrazole rings are approximately planar, with maximum deviations of 0.017 (2) and 0.010 (2) Å , and the dihedral angles between the pyrazole and phenyl rings are 83.63 (11) and 70.07 (12) . In one molecule, an intramolecular C-HÁ Á ÁO hydrogen bond with an S(6) ring motif is observed. In the crystal, intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the molecules into two-dimensional networks parallel to the ab plane.

Comment
Antibacterial and antifungal activities of the azoles are most widely studied and some of them are in clinical practice as anti-microbial agents. However, the azole-resistant strains had led to the development of new anti-microbial compounds. In particular, pyrazole derivatives are extensively studied and used as anti-microbial agents. Pyrazole is an important class of heterocyclic compounds and many pyrazole derivatives are reported to have the broad spectrum of biological properties such as anti-inflammatory, antifungal, herbicidal, anti-tumour, cytotoxic, molecular modelling and antiviral activities. Pyrazole derivatives also act as anti-angiogenic agents, A3 adenosine receptor antagonists, neuropeptide YY5 receptor antagonists as well as kinase inhibitor for treatment of type 2 diabetes, hyperlipidemia, obesity and thrombopiotinmimetics. Recently urea derivatives of pyrazoles have been reported as potent inhibitors of p38 kinase. Since the high electronegativity of halogens (particularly chlorine and fluorine) in the aromatic part of the drug molecules play an important role in enhancing their biological activity, we are interested to have 4-fluoro or 4-chloro substitution in the aryls of 1,5-diaryl pyrazoles. As part of our on-going research aiming the synthesis of new anti-microbial compounds, we have reported the synthesis of novel pyrazole derivatives and their microbial activities (Ragavan et al., 2009. The title compound consists of two crystallographically independent molecules, with similar geometries, namely molecules A and B and exist in keto-form. This indicates that the compound undergoes an enol-to-keto tautomerism during the crystallization process with the bond lengths of C═ O being 1.267 (2) and 1.254 (2) Å in molecule A and B, respectively.
Experimental 3-Isobutyl-4-(phenylthiol)-1H-pyrazol-5-ol was synthesized using the method available in the literature . It was then dissolved in 1:1 mixture of THF/Water. Oxone was then added and the solution was stirred at room temperature for 3 h. The reaction mixture was diluted with water (20 ml) and then extracted with ethylacetate (2 x 50 ml).
The combined extract was washed with water (20 ml) and brine solution. The titled compound was recrystallized using the

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.