Key Intermediates: A simple and Highly Selective Synthesis of 5-amino-1-aryl-1H-pyrazole-4-carbonitriles for Applications in the Crop Protection

PLEM, S.C.; MÜLLER, D.M.; MURGUÍA, M.C.

Advances in Chemical Engineering and Science

Scientific Research Publishing, Inc.

Año: 2015 vol. 5 p. 239 - 261

2160-0406

A series of six pyrazoles was synthesized by Michael-type addition reaction. The molecules 5-amino-1-aryl-1H-pyrazole-4-carbonitrile (3a-f) were synthesized from (ethoxymethylene)malononitrile (1) and fluorinated and non-fluorinated aryl hydrazines (2a-f) using ethanol and fluorinated ethanol as solvents at reflux. An excellent regio-selectivity was found when pyrazole derivatives were formed as an exclusive product. No other regioisomer or uncyclised hydrazide were observed. Their structures were confirmed by spectroscopy data (1H, 13C, 19F, COSY; HSQC, HMBC, MS). The yields ranged from good to excellent (47%-93%) under mild reaction conditions. It would indicate a high selectivity in the one-step work procedure. These products (3a-f) and derivatives have a potential academic and industrial use as key intermediates, in special, for application in crop protection.