azlactones

https://doi.org/10.1351/goldbook.A00559
Oxazol-5(4H)-ones I, compounds derived by cyclization of N-acyl α-amino carboxylic acids,
RC(=O)NHCR2C(=O)OH
, through formal loss of the elements of water. 4-Hydrocarbylideneazlactones II are often referred to as 'unsaturated azlactones'.
A00559-2.png
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1321 (https://doi.org/10.1351/pac199567081307)