Transition-Metal-Free Intramolecular Radical Aminoboration of Unactivated Alkenes.

An efficient transition-metal-free cyclizing radical aminoboration of unactivated alkenes is reported. The B2(OH)4 reagent was used as the boron source, and the interaction between B2(OH)4 and an aryloxyamide N-radical precursor enabled the chain reaction to be initiated upon irradiation in the absence of any catalyst. This transformation proceeds via cyclization of an N-radical with subsequent intermolecular C-radical borylation. The cascade shows a broad scope and provides a wide range of high-value cyclic 1,2-aminoboronic esters.