Synthesis and biological activity of a novel fungicide, pyraziflumid.

Pyraziflumid was discovered as a novel SDHI fungicide chemically characterized by the 3-(trifluoromethyl)pyrazine-2-carboxamide group. This chemical series showed particularly high fungicidal activities against a broad spectrum of plant diseases in the case of N-(biphenyl-2-yl) as well as N-(1,1,3-trimethylindan-4-yl)carboxamides. Various N-(biphenyl-2-yl)pyrazine-2-carboxamides were synthesized, and their structure-activity relationships were studied. The optimization of the fungicidal performance of the series finally led to the identification of pyraziflumid, which could control a wide range of plant diseases. In this report, details of the structure-activity relationships from the lead compound to pyraziflumid are described.