Je. Macor et al., AN UNUSUAL BY-PRODUCT FROM A NONSYNCHRONOUS REACTION BETWEEN ETHYL 1,2,4-TRIAZINE-3-CARBOXYLATE AND AN ENAMINE, Chemical communications, (9), 1998, pp. 983-984
The main product from the reaction of ethyl 1,2,4-triazine-3-carboxyla
te 3 and the pyrrolidine enamine of N-tertbutoxycarbonylpiperidone 2 w
as an azabicyclo[3.2.1]octane 4 which resulted not from a Diels-Alder
reaction, but from a series of non-synchronous steps, demonstrating a
heretofore unknown reaction pathway for the electron-deficient diene 3
and electron-rich dienophile 2.