oxazolone

File:5-(4H)-oxazolone.svg

Oxazolone is a chemical compound and functional group, with the molecular formula C₃H₃NO₂. It was named in-line with the Hantzsch–Widman nomenclature and is part of a large family of oxazole based compounds. There are a total of 5 structural isomers of oxazolone; 3 according to the location of the carbonyl group and 2 more according to the location of the double bond C=X (with X= N or C):

• 2-(3H)oxazolone
• 2-(5H)oxazolone
• 4-(5H)-oxazolone
• 5-(2H)-oxazolone
• 5-(4H)-oxazolone

File:Oxazolones.png

The 4-oxazolone motif, which is also formally a lactam, is present in a number of drugs (fenozolone, thozalinone, cyclazodone, reclazepam etc.).

Substituted 5-oxazolones may also be regarded as the cyclization products of N-acyl α-amino acids, making them lactones, and are sometimes referred to as azlactones.{{GoldBookRef|title=azlactones| file = A00559}}{{cite journal|last1=K. Mukerjee|first1=Arya|title=Azlactones: Retrospect and Prospect|journal=Heterocycles|date=1987|volume=26|issue=4|pages=1077|doi=10.3987/R-1987-04-1077|doi-access=free}}