New approach to the synthesis of cyazofamid, fungicide

A robust and versatile six-step synthetic approach has been developed for the synthesis of cyazofamid, a highly selective fungicide used for controlling oomycete pathogens, particularly phytophthora infestans, the causing agent of late blight in potatoes. The pivotal step involves the construction of an imidazole ring via the cyclization of 2-amino-1-(p-tolyl)ethan-1-one with ethyl 2,2,2-trichloroacetimidate. Other key transformations in the synthesis include the dehydration of amide to nitrile, the regioselective chlorination, and N-sulfamoylation of the imidazole ring. All the reactions are performed on a preparative scale, affording an overall yield of 28 %. This approach employs non-hazardous, readily available reagents and offers improved regioselectivity, presenting a practical advancement in the synthesis of cyazofamid.