Synthesis and antibacterial activity of some new 1-heteroaryl-5-amino-3H/methyl-4-phenylpyrazoles

The regioselective synthesis of 1-heteroaryl-5-amino-4-phenylpyrazoles 3a-g and I -heteroaryl-5-amino-3-methyl-4-phenylpyrazoles 3h-n was achieved by the treatment of heteroarylhydrazines la-g with alpha-phenylforniylacetonitrile 2a and alpha-phenylacetylacetonitrile 2b, respectively. The structures of the compounds 3 were established by the combined use of H-1 and C-13 NMR spectroscopy. All the fourteen compounds were tested for their in vitro antibacterial activity against three Gram-positive and two Gram-negative bacteria. Six compounds 3a, 3d, 3e, 3g, 31, and 3n frorn this series were found to be equipotent or more potent than the commercial antibiotics (Linezolid and Cefroxime axetil). (c) 2005 Elsevier Ltd. All rights reserved.