Metal-Free Regioselective Direct C(4)−H Amination of Quinazoline with N-fluorobenzenesulfonimide

A facile C−H amination of quinazoline employing N-fluorobenzenesulfonimide (NFSI) as the amination source has been disclosed in the absence of any metal, oxidant or additive. The methodology shows a board range of quinazolines with different functional groups in moderate to good yields up to 87 %. Furthermore, gram-scale reaction, desulfonylation to amine and synthesis of pharmaceutical intermediate were also investigated, which demonstrates potential applications in medicinal chemistry. A plausible amination mechanism is proposed via F⁺ transfer accompanied by the removal of one molecule of PhSO₂F. DFT studies with experimental work suggest that the mechanism via F⁺ transfer is more favorable than the free radical one.