Synthesis of Difluorocyclopropanes via Visible‐Light‐Mediated [1+2] Cycloaddition of Diazo Esters with gem‐Difluoroalkenes and Evaluation of their Antifungal Activity

Abstract In this work, we reported a method for construction of difluorocyclopropanes through visible light‐promoted [1+2] cycloaddition reaction of aryl diazo esters with gem ‐difluoroalkenes. The reaction proceeds under mild conditions, encompasses a wide range of substrates (36 examples), exhibits good tolerance to various substituents, and demonstrates a diastereoselectivity of >20:1. Additionally, antifungal activity evaluation revealed that these derivatives exhibited certain activity, the EC 50 values for the products towards Botrytis cinerea and Rhizoctonia solani were measured to be 1.51 and 1.36 μM, respectively, which are significantly lower than those of commercial fungicides Hymexazol and Azoxystrobin. This work not only provides an efficient method for the synthesis of difluorocyclopropanyl derivatives, but reveals their potential applications in fungicide creation.