Rhodium(iii)-catalysed carboxylate-directed C-H functionalizations of isoxazoles with alkynes.

An efficient oxidative [4+2] annulation of isoxazolyl-4-carboxylic acids with internal alkynes proceeded in the presence of the [Cp*RhCl2]2 catalyst. Oxidants controlled the formation of pyranoisoxazolones and isoquinolines. A decarboxylative approach for the hydroarylation of alkynes with isoxazolyl-4-carboxylic acids was also developed in the presence of the [Cp*Rh(CH3CN)3][SbF6]2 catalyst.