Computational Study on Chemoselective Difunctionalization of Unactivated Alkenes with Radical-mediated Remote Functional Group Migration.

A computational study of the radical-mediated chemoselective difunctionalization of the tertiary alcohol substituted aliphatic alkenes is carried out employing density functional theory (DFT) and high-level coupled-cluster methods, such as coupled-cluster singles and doubles with perturbative triples [DLPNO-CCSD(T)]. Our results indicate that the cyclic vinyl radical plays an important role in the progression of the reactions. Our computations demonstrated that the chemoselective difunctionalization of unactivated alkenes with radical-mediated remote functional group migration is suitable for the 5- and 6-exo-dig cyclization, as opposite to 3- and 4-exo-dig cyclization suffering from cyclic intermediate with high energy. Our results show that the migration of nitrile group is more preferable than that of alkynyl group for the molecules including both cyano group and alkynyl group. For the 5- and 6-exo-dig cyclization, the rate-determining step is the homolysis of the C-C σ-bond in the cyclic intermediate, which results in the hydroxyl alkyl radical.