In organic chemistry, a dioxazolone is a cyclic carbonate incorporated into CNO ring. It is an uncommon heterocyclic compound.  They arise by the phosgenation of hydroxamic acids:
:RC(O)NHOH  +  COCl  →   RC=NOCO  +  2 HCl
Although dioxazolones are often explosive, they are of interest as precursors to isocyanates:
:RC=NOCO  →  R-N=C=O  +  CO
Dioxazolones have attracted attention as reagents for the preparation of amides.