Hong-Yu Tian

Electrochemically Initiated Oxidative Amination of Benzoxazoles Using Tetraalkylammonium Halides As Redox Catalysts

An electrochemically promoted coupling of benzoxazoles and amines has been developed, leading directly to the formation of 2-aminobenzoxazoles. The chemistry utilizes catalytic quantities of a tetraalkylammonium halide redox catalyst and is carried out under constant current conditions in a simple undivided cell. The use of excess chemical oxidant or large amounts of supporting electrolyte is avoided. This greatly simplifies the workup and isolation process and leads to a reduction in waste.

Electrochemically catalyzed amino-oxygenation of styrenes: n-Bu4NI induced C–N followed by a C–O bond formation cascade for the synthesis of indolines

Efficient electrochemical amino-oxygenation of styrenes has been developed for the synthesis of 3-methoxyindolines and 3-ethoxyindoline, using a simple beaker-type undivided cell with n-Bu4NI serving as a redox catalyst under constant current electrolysis (CCE) conditions. The chemistry proceeds in a paired electrolysis mode, avoiding the utilization of external oxidants and bases and therefore represents an environmentally benign means. The process also works in the absence of an additional conducting salt. Gram-scale reaction further demonstrates the practicability of the protocol. Proton NMR spectroscopy was used to demonstrate that the amino-oxygenation of N-(2-vinylphenyl)sulfonamides likely involves the initial iodoamination of the alkene, followed by nucleophilic substitution of the methoxide/ethoxide generated at the cathode.

Electrochemical oxidation of catechols in the presence of enaminone: exclusive α- arylation

Anodic oxidation of catechols in the presence of enaminones serving as potential doubly nucleophiles is examined using cyclic voltammetry and preparative electrolysis methods. Selective α-arylation is observed, which is consistent with that from the chemical oxidation approach. The results demonstrate that formation of either indoles or α-arylated products is depended on the nature of the polarized enaminone.