Modular assembly of amines and diborons with photocatalysis enabled halogen atom transfer of organohalides for C(sp)-C(sp) bond formation.

In the past few years, the direct activation of organohalides by ligated boryl radicals has emerged as a potential synthetic tool for cross-coupling reactions. In most existing methods, ligated boryl radicals are accessed from NHC-boranes or amine-boranes. In this work, we report a new photocatalytic platform by modular assembly of readily available amines and diboron esters to access a library of ligated boryl radicals for reaction screening, thus enabling the cross-coupling of organohalides and alkenes including both activated and unactivated ones for C(sp)-C(sp) bond formation by using the assembly of DABCO A1 and BNepB1. The strategy features operational simplicity, mild conditions and good functional group tolerance. A range of organohalides including activated alkyl chlorides, alkyl bromides (1°, 2° and 3° C-Br) as well as aromatic bromides are applicable in the strategy. Experimental and computational studies rationalize the proposed mechanism.