Oxazol-5(4H)-ones I, compounds derived by @C01494@ of N-acyl α-amino @C00852@,
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 [Terms] [Paper]