On triazoles XVI . The reaction of 5‐amino‐1,2,4‐triazoles with β‐ and γ‐oxo esters. A novel N ‐carbonylation reaction

5‐Amino‐1,2,4‐triazoles reacted with alifatic β‐oxo‐esters to yield besides the unexpected 1,2,4‐triazolo‐[1,5‐ a ]‐1,3,5‐benzotriazepin‐5‐one derivative 7 either the corresponding esters 5 and 6 or a 1:2 condensation product 8. To the contrary alicyclic and heterocyclic β‐oxo‐esters formed in the above reaction only derivatives 7. The proposed mechanism of the formation of 7 involving a novel N ‐carbonylation reaction was proved by the isolation of the by‐products and the intermediate of the reaction. Repeating the above reaction with a γ‐oxo‐ester, namely the ethyl levulinate, derivatives 17 and 18 , respectively, representing two new ring systems were obtained.