NBS-mediated C-selenocyanation/cyclization of enaminones with KSeCN: a mild and efficient synthesis of 2-aminoselenazoles

A simple, exogenous-base-free, and NBS-mediated C-selenocyanation/cyclization reaction of enaminones with KSeCN under mild conditions, providing a facile route to 2-aminoselenazole products, has been developed. This efficient protocol is postulated to first undergo the NBS-oxidated polarity reversal of the reactive SeCN- anion to form N-selenocyanosuccinimide as an electrophilic selenium source, which can induce the C-selenocyanation of enaminones and enamino esters, followed by a nucleophilic cyclization promoted by in-situ yielded HBr.