Computational Design of a Tetrapericyclic Cycloaddition and the Nature of Potential Energy Surfaces with Multiple Bifurcations

An ambimodal transition state (TS) that leads to formation of four different pericyclic reaction products ([4 + 6]-, [2 + 8]-, [8 + 2]-, and [6 + 4]-cycloadducts) without any intervening minima has been designed and explored with DFT computations and quasiclassical molecular dynamics. Direct dynamics simulations propagated from the ambimodal TS show the evolution of trajectories to give the four cycloadducts. The topography of the PES is a key factor in product selectivity. A good correlation is observed between geometrical resemblance of the products to the ambimodal TS (measured by the RMSD) and the ratio of products formed in the dynamics simulations.

Automated summary

An ambimodal transition state (TS) has been designed and explored using DFT computations and quasiclassical molecular dynamics, which leads to the formation of four different pericyclic reaction products without any intervening minima. Direct dynamics simulations starting from the ambimodal TS demonstrate the evolution of trajectories that result in the formation of the four cycloadducts. The product selectivity is influenced by the topography of the potential energy surface (PES), and a correlation is observed between the geometrical resemblance of the products to the ambimodal TS (measured by RMSD) and the ratio of products formed in the dynamics simulations.