Abstract A series of 2-oxazinones 1-8 were synthesized from the cycloaddition reactions of oxetanes with isocya-nates by utilizing the complex of diphenyltin diiodide with hexamethylphosphoric triamide (HMPA) as a catalyst. Moreover, the reactions with carbodiimides proceeded under milder conditions with the same catalyst system, and gave 2- iminooxazines, 9 and 10, in high yields.
