Synthesis of 3,4,5-trisubstituted isoxazoles via sequential [3+2] cycloaddition/silicon-based cross-coupling reactions

A [3 + 2] cycloaddition reaction between alkynyldimethylsilyl ethers and arlyl and alkyl nitrile oxides to produce isoxazolylsilanols has been developed. The cross-coupling reactions of these heterocyclic silanols with a variety of aryl iodides affords 3,4,5 -trisubstituted isoxazoles. This sequential process allows for rapid variation of substituents at the 3 4, and 5 positions of the isoxazole.