Room Temperature Decarboxylative and Oxidative [2+2+2] Annulation of Benzoic Acids with Alkynes Catalyzed by an Electron-Deficient Rhodium(III) Complex.

It has been established that an electron-deficient (η5 -cyclopentadienyl)rhodium(III) [CpE RhIII ] complex is capable of catalyzing the decarboxylative and oxidative [2+2+2] annulation of benzoic acids with alkynes to produce substituted naphthalenes at room temperature. The appropriate choice of the additive and the solvent is crucial for this transformation. This catalyst system allowed use of oxygen as a terminal oxidant and broadened the substrate scope including both aromatic and aliphatic alkynes. In this catalysis, the electron deficient nature of the CpE RhIII catalyst would cause the strong rhodium-π interaction, which accelerates the decarboxylation as well as the C-H bond cleavage.