Aromatic aldehydes and hippuric acid in acetic anhydride undergoes classical Erlenmeyer synthesis in the presence of a catalytic amount of Montmorillonite K-10 to afford the corresponding azlactones in excellent yields with high selectivity. The azlactone formation does not proceed in the absence of either acetic anhydride or Montmorillonite.
![5(4H)-Oxazolone,4-[[2-(acetyloxy)phenyl]methylene]-2-phenyl- Structure](https://image.chemsrc.com/caspic/183/52900-70-6.png)