Metal and base free synthesis of primary amines via ipso amination of organoboronic acids mediated by [bis(trifluoroacetoxy)iodo]benzene (PIFA)

Abstract

A metal and base free synthesis of primary amines has been developed at ambient temperature through ipso amination of diversely functionalized organoboronic acids, employing a combination of [bis(trifluoroacetoxy)iodo]benzene (PIFA)–N-bromosuccinimide (NBS) and methoxyamine hydrochloride as the aminating reagent. The amines were primarily obtained as their trifluoroacetate salts which on subsequent aqueous alkaline work up provided the corresponding free amines. The combination of PIFA–NBS is found to be the mildest choice compared to the commonly used strong bases (e.g. n-BuLi, Cs₂CO₃) for activating the aminating agent. The reaction is expected to proceed via activation of the aminating reagent followed by B–N 1,2-aryl migration.