Rh(III)-Catalyzed [3 + 3] Annulation of Cyclopropenones with Iodonium Ylides for the Synthesis of 2,5-Dihydrochromenediones

We report an efficient Rh(III)-catalyzed [3 + 3] annulation reaction between cyclopropenones and iodonium ylides. This process proceeds <i>via</i> a ring-opening/ring-closing mechanism to afford a diverse range of 2,5-dihydrochromenedione derivatives. The reaction demonstrates a broad substrate scope and good functional group tolerance, with moderate to excellent yields. The synthetic utility of this methodology is further highlighted by a gram-scale synthesis and successful derivatization of the resulting 2,5-dihydrochromenediones.