Synthesis and anti-TMV activity of novel N-(3-alkyl-1H-pyrazol-4-yl)-3-alkyl-4-substituted-1H-pyrazole-5-carboxamides

In order to investigate the biological activity of novel bis-pyrazole compounds, a series of N-(3-alkyl-5-(N-methylcarbamyl)-1H-pyrazol-4-yl)-3-alkyl-4-substituted-1H-pyrazole-5-carboxamides were designed and synthesized with ethyl 3-alkyl-1H-pyrazole-5-carboxylate 1 as starting materials. N-Methyl-3-alkyl-4-amino-1H-pyrazole-5-carboxamides 6 were obtained from 1 via 5 steps. 3-Alkyl-4-substitued-1H-pyrazole-5-carboxyl chlorides 4a, 4b, 11a, 11b, 11c or 12 were also obtained from 1 via several steps. Target compounds 7a–7g were obtained after the reaction of 6 with the above 1H-pyrazole-5-carboxyl chlorides. Preliminary bioassay showed some compounds possessing good inactivation effect against TMV (tobacco mosaic virus). Compound 7a showed higher activity superior to ningnanmycin at a concentration of 5.0×10−4g/mL and equal activity at 1.0×10−4g/mL; 7b and 7c showed equal activity to virazole both at concentrations of 5.0×10−4g/mL and 1.0×10−4g/mL.