XY–ZH Systems as Potential 1,3-Dipoles. Part 50: Phenylselenyl Halide Induced Formation of Cyclic Nitrones from Alkenyl Oximes

Oximes possessing γ-, δ or ω-alkenyl substituents are cyclised by phenylselenyl bromide, or by phenylselenyl chloride and an appropriate silver salt to the corresponding cyclic nitrones; the seleno nitrones undergo facially specific cycloaddition reactions with N-methylmaleimide; bis(alk-γ,δ-enyl) ketones undergo regiospecific cyclisation and stereospecific intramolecular cycloaddition to furnish spirocyclic products.