Mechanism of Permanganate-Promoted Dihydroxylation of Complex Diketopiperazines: Critical Roles of Counter-cation and Ion-Pairing.

ABSTRACT: The mechanism of permanganate-mediated dual C-H oxidation of complex diketopiperazines has been examined with density functional theory computations. The products of these oxidations are enabling intermediates in the synthesis of structurally diverse ETP natural products. We evaluated, for the first time, the impact of ion-pairing and aggregation states of the permanganate ion and counter-cations, such as bis(pyridine)-silver(I) (Ag⁺) and tetra- n-butylammonium (TBA⁺), on the C-H oxidation mechanism. The C-H abstraction occurs through an open shell singlet species, as noted previously, followed by O-rebound and a competing OH-rebound pathway. The second C-H oxidation proceeds with a second equivalent of oxidant with lower free energy barriers than the first C-H oxidat

SUBMITTER: Haines BE 

PROVIDER: S-EPMC6209109 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature