FeCl2-catalyzed intramolecular chloroamination reactions

2-Alkenyloxycarbonyl azides 1 and 2-alkynytoxycarbonyl azides 3 undergo in the presence of trimethylsilyl chloride and catalytic amounts of FeCl2 an intramolecular chloroamination (aminochlorination) reaction (Procedure 1). The corresponding oxazolidinones 2 and 4 are formed in moderate to excellent yields (47-99%). The same reagent combination can be employed to convert azides 6 of gamma,delta-unsaturated carboxylic acids into the corresponding lactams 7. The latter reaction is best conducted as a one-pot reaction (Procedure 2) starting from the acids 5 without isolation of the corresponding azides (57-75% yield).