A series of β-keto esters were synthesized from heteroaryl esters and ethyl acetate using LiHMDS as base at -50 to -30 °C. The increase in yields of cross condensed product were observed and the percentage of self condensed product was reduced drastically by applying the suitable base (LiHMDS), solvent and the minimum amount of ethyl acetate. All these β-keto esters were characterized using 1H NMR, 13C NMR and mass spectral data. A plausible mechanism is also depicted to prove the formation of trans-esterified products. All the synthesized compounds were subjected to test for their cytotoxicity towards various cancer cell lines and also tested for their antimicrobial activity towards various bacterial and fungal strains and some of them were found to have promising activity. © 2012 Elsevier Ltd. All rights reserved.

Vijayakumar V

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Karthikeyan S

Department of Biotechnology

School of Bio Sciences and Technology

Venkat Ragavan R

Rajesh K

Palakshi Reddy B

Suchetha Kumari N.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Bioorganic & Medicinal Chemistry Letters

α-Oxy/thio substituted β-keto esters were synthesized through an efficient cross-Claisen condensation of oxy/thio substituted acetic acid ethyl esters with acid chlorides, which in turn converted in situ into 4-oxy/thio substituted-1H-pyrazol-5(4H)-ones by the addition of hydrazine and its derivatives. This method has been found to be extremely fast, general, and useful toward the synthesis of inaccessible pyrazolones and synthetically demanding 4-oxy/thio substituted pyrazolones. © 2010 HeteroCorporation.

Journal of Heterocyclic Chemistry

A novel route to 4-oxy/thio substituted-1H-pyrazol-5(4H)-ones via efficient cross-Claisen condensation

The asymmetric unit of the title compound, C11H 12N2O, consists of two crystallographically independent molecules (A and B) with similar geometries. Both molecules exist in a keto form, the C=O bond length being 1.286 (2) Å in A and 1.283 (2) Å in B. The dihedral angles between the pyrazole ring and the attached phenyl ring are 43.28 (12) and 46.88 (11)°, respectively, for A and B. The ethyl unit in molecule B is disordered over two positions with a siteoccupancy ratio of 0.508 (5):0.492 (5). In the crystal, each of the independent molecules forms a centrosymmetric dimer with an R 2 2(8) ring motif through a pair of N -H⋯O hydrogen bonds. These dimers are further connected into a threedimensional network by intermolecular N -H⋯O and C -H⋯O hydrogen bonds. Intermolecular C -H⋯π interactions are also present.

Fulltext

Acta Crystallographica Section E Structure Reports Online

5-Ethyl-4-phenyl-1H-pyrazol-3(2H)-one

The title compound, C 6H 10N 2O, is a zwitterionic pyrazole derivative. The crystal packing is predominantly governed by a three-center iminium-amine N + - H⋯O -⋯H - N inter-action, leading to an undulating sheet-like structure lying parallel to (100).

3-Ethyl-4-methyl-1H-pyrazol-2-ium-5-olate

The asymmetric unit of the title compound, C10H 10N2O, contains two crystallographically independent molecules with similar geometries, which exist in the keto form. The C=O bond lengths are 1.2878 (12) Åin molecule A and 1.2890 (12) Åin molecule B, indicating that the compound undergoes enol-to-keto tautomerism during the crystallization process. In molecule A, the pyrazole ring is approximately planar [maximum deviation = 0.007 (1) Å] and forms a dihedral angle of 36.67 (6)° with the attached phenyl ring. In molecule B, the dihedral angle formed between the pyrazole ring [maximum deviation = 0.017 (1) Å] and the phenyl ring is 41.19 (6)°. In the crystal, intermolecular N - H⋯O hydrogen bonds link neighbouring molecules into dimers generating R 22(8) ring motifs. These dimers are linked into ribbons along [101] via intermolecular N - H⋯O hydrogen bonds, forming R 42(10) ring motifs.

4-Methyl-5-phenyl-1H-pyrazol-3(2H)-one

Novel 1,5-diaryl pyrazole derivatives viz. 5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-carboxamides (2a-e, 3, 3a-f), 2-(5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-yl)thiazoles (6a-c,7, 8, 9a-c, 10, 11) were synthesized by varying the active part (amide group) of pyrazole, characterized using IR, (1)H NMR, mass spectral data and screened for their antibacterial activity against Escherichia coli (ATTC-25922), Staphylococcus aureus (ATTC-25923), Pseudomonas aeruginosa (ATTC-27853), Klebsiella pneumonia. Similarly all these compounds were screened for their antifungal activity against Aspergillus flavus (NCIM No. 524), Aspergillus fumigates (NCIM No. 902), Penicillium marneffei and Trichophyton mentagrophytes. Interestingly all the synthesized compounds exhibited good antibacterial (except 2a-c, 8, 9a) and antifungal activity (except 2a-c, 6a, 8, 9a).

European Journal of Medicinal Chemistry

Synthesis and antimicrobial activities of novel 1,5-diaryl pyrazoles

Simple, fast and efficient synthesis of β-keto esters from the esters of heteroaryl compounds, its antimicrobial study and cytotoxicity towards various cancer cell lines

Journal	Data powered by TypesetBioorganic & Medicinal Chemistry Letters
Publisher	Data powered by TypesetElsevier BV
ISSN	0960-894X
Open Access	0