Abstract Reaction of N-(α-acetoxy) 4-pyridylmethyl]-3, 5-dimethylbenzamide 3 with methyl and ethyl isocyanates afforded 1, 3-dimethyl and 1, 3-diethyl-4-(3, 5-dimethylbenzoylamino)- 2-oxoimidazolidine-5-spiro-4′-[1′, 4′-dihydro-1′-acetyl] pyridine 6a, b, respectively. However, the reaction of 3 with isopropyl, t-butyl and phenyl isocyanates gave the corresponding N, N′-diurea and the dimerization compound 8. The structure of 6a was ...