Bromonium-catalyzed 1,2-diamination of various conjugated alkenes.

Alkene functionalization via cyclic halonium intermediates is highly effective for stereocontrol, and a catalytic approach further expands this strategy, offering access to more advanced functionalization. Although various studies have utilized halonium species, expanding their scope to electron-deficient or π-conjugated alkenes has remained challenging. In this report, using a bromonium catalytic system, we achieved the stereoselective intermolecular 1,2-diamination of various α,β-unsaturated carbonyl compounds and π-extended alkenes. The direct use of hazardous Br2 was avoided by generating the active species, dibromamine-Ns (Br2NNs), in situ from stable dichloramine-Ns (Cl2NNs) and NaBr. The reaction proceeded with complete anti-selectivity, and mechanistic studies revealed a stereoselective pathway involving catalytic aziridination followed by ring opening. The resulting nosyl-protected diamines can be flexibly deprotected and derivatized, providing rapid access to useful scaffolds such as unnatural amino acids and nitrogen-containing functional molecules.