Ene reactions of acyl nitroso intermediates with alkenes and their halocyclization

Highly reactive acyl nitroso intermediates were formed in situ by transition metals-catalyzed hydrogen peroxide oxidation of hydroxamic acids 1a–b and these transient species trapped with alkenes 2a–c to afford the corresponding ene products 3a–d and 4b up to 91% yield, and halocyclization of 3d gave substituted oxazolidinone 5a in 77% yield.