Generation of an 4‐Isoxazolyl Anion Species: Facile Access to Multifunctionalized Isoxazoles

Abstract

AbstractA direct functionalization of unsubstituted isoxazole (1) was achieved by generation of 4‐isoxazolyl anion species (3). An efficient 4‐iodination of isoxazole and halogen–metal exchange reaction using a turbo Grignard reagent (iPrMgCl⋅ LiCl) were essential for the generation of 3, which reacted with various electrophiles to give 4‐functionalized isoxazoles in good to high yields. Isoxazolyl boronate, boronic acid, and stannane were also synthesized as useful building blocks from 1. The current methods enabled us to synthesize multi‐functionalized isoxazoles by introducing each substituent into the desired positions. Furthermore, total synthesis of triumferol, which was isolated from Triumfetta rhomboidea, was achieved from 1 in only three steps.