Fungicides are important in modern agriculture. In order to counter resistances, new fungicides are needed. However, it is challenging to find new structural motifs for compounds with fungicidal activities. Indole derivatives are commonly found both in natural products and in pharmaceuticals or agrochemicals, but are generally not used in commercially available fungicides.

Jianyou Mao, Nanjing Tech University, China, Jinlin Zhang, Hebei Agricultural University and Biological Control Center of Plant Diseases and Plant Pests of Hebei Province, Baoding, China, and colleagues have developed a practical one-pot synthesis of a variety of 2-arylindole derivatives (pictured) and tested their fungicide activity. The team started from a range of 1-fluoro-2-(phenoxymethyl)benzene derivatives, which were reacted with different arylaldehydes and the silylamide base LiN(SiMe₃)₂, using CsF as an additive and cyclopentyl methyl ether (CPME) as the solvent. The reactions were performed at 110 °C.

The desired 2-arylindole derivatives were obtained in generally moderate to high yields. The team performed a preliminary screening of the fungicidal activities of the products against twelve plant pathogens, using an antifungal bioassay. They found several compounds with promising activities against pathogens, e.g., Rhizoctonia cerealis, which can affect grains and lead to yield losses. According to the researchers, 2-arylindoles could warrant further investigation as fungicide candidates.

• 2-Arylindoles: Concise Syntheses and a Privileged Scaffold for Fungicide Discovery,
  Jingqian Huo, Lai Chen, Helong Si, Shitao Yuan, Jiahui Li, Haijiao Dong, Shiqi Hu, Jinglei Huo, Song Kou, Dan Xiong, Jianyou Mao, Jinlin Zhang,
  J. Agric. Food Chem. 2022.
  https://doi.org/10.1021/acs.jafc.1c08085