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

Abstract

Abstractα‐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. J. Heterocyclic Chem., (2011).

4-{[5-(4-Chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazol-3-yl]carbonyl}-N-ethylpiperazine-1-carboxamide

“…As part of our ongoing research aiming on the synthesis of novel pyrazole derivatives as new antimicrobial compounds, herein we report the synthesis of title compound (Ragavan et al, , 2010Ragavan & Vijayakumar, 2011) The asymmetric unit of title compound (Fig. 1) (Allen et al, 1987) and angles are within normal ranges and comparable to those closely related structures (Shahani et al, 2009(Shahani et al, , 2010a.…”

“…For our ongoing research on the synthesis of pyrazole derivatives with antimicrobial activity, see: Ragavan et al (2009Ragavan et al ( , 2010; Ragavan & Vijayakumar (2011). For related structures, see: Shahani et al (2009Shahani et al ( , 2010a.…”