Molecular Dynamics\nof the Davies Ambimodal C–H\nFunctionalization/Cope Rearrangement Reaction

The mechanism of the dirhodium-catalyzed combined C–H\nfunctionalization/Cope\nrearrangement (CH/Cope) reaction discovered by the Davies group has\nbeen investigated with density functional theory (DFT) calculations\nand quasi-classical molecular dynamics (MD) simulations. Computations\nfrom the Davies group previously showed that there is a post-transition\nstate bifurcation leading to a direct CH reaction and also to the\nCH/Cope product. While this work was in preparation, the Tantillo\ngroup and the Ess group independently reported quantum mechanical\nand molecular dynamics studies on the dirhodium-tetracarboxylate-catalyzed\ndiazoester CH/Cope and CH insertion reactions with 1,3-cyclohexadiene\nand 1,4-cyclohexadiene, respectively. The Tantillo group cited “dynamic\nmismatching” to explain the origins of the low yield of CH/Cope\nproducts in some experiments; the Ess group explained the origins\nof product selectivity from the perspective of TS vibrational modes\nand their synchronization that occurs at the entropic intermediates.\nWe report quasi-classical trajectories for the reaction of the carbene\nwith 1-methylcyclohexene that afford both the CH/Cope and C–H\ninsertion products. After passing through the transition state that\ninvolves mostly hydrogen transfer, momentum drives the reaction trajectories\ntoward the CH/Cope products.