Oxidative Addition Promoted C-C bond cleavage in Rh-mediated Cyclopropenone Activation: A DFT Study

Computational characterization of the oxidation addition promoted in rhodium catalyzed cyclopropenones activation and conversion via quinolyl, pyridyl, and nitrone directed C–H activation is presented. Our theoretical studies found that a common catalytic cycle for these reactions starts with Rh(III)-mediated concerted metalation–deprotonation or electrophilic deprotonation, to afford the aryl-Rh(III) intermediate. Oxidative addition of cyclopropenone to aryl-Rh(III) then gives a cyclorhoda(V)butanone intermediate, leading to cleavage of the cyclopropene moiety through a concerted three-membered cyclic transition state. Subsequent reductive elimination of the intermediate generates a target C(aryl)–C(acyl) bond. The final product is produced by further transformations with concomitant regeneration of active Rh(III) catalyst. The previously proposed carbonyl insertion mode for activation of cyclopropenones is excluded by the DFT calculations. The directing group effect in cyclopropenone activation was theo...