A recent study has! shown that N-ethoxycarbonylthioamides (1) react with reagents possessing two adjacent nucleophilic sites (" 2, NHR, OH) at both thiocarbonyl and carbonyl groups to form five-membered, carbonyl-containing heterocyclic rings. Thus reactions with hydrazines and hydroxylamines yield dihydro-1, 2, 4-triazolones and 1, 2, 4-oxadiazolones, respectively.'In view of these results, it was of interest to investigate the behavior of 1 ...