A DFT study on a mutipathways, one product reaction: Initially divergent radical reactions reconverge to form a single product

The mechanism for initially divergent radical reactions reconverging to form a single product is studied using density functional theory calculations. The calculation results suggest that there are six possible pathways from reactants to products. The free energy barriers of the rate-determining steps of each pathway are almost equal. Thus, different from usual reaction, the selectivity of this reaction is determined by the relative value of free energy barriers of the two competitive reactions, that is, cyclization and bimolecular trapping, rather than that of rate-determining steps. In all reaction pathways, cyclization reaction is more competitive than bimolecular trapping reaction due to its low free energy barrier. In addition, the free energy barriers of bimolecular trapping reaction between Bu3SnH and reactants are all lower than that of NCC6H11. However, Bu3SnH is not always suitable due to its large steric repulsion. © 2014 Wiley Periodicals, Inc.