The alcoholysis of 1,5-diazabicyclo[3.3.0]ocatane-2,4,6,8-tetrone and some derivatives

Article abstract of DOI:10.1002/ardp.19863190611

Both rings of 1,5-diazabicyclo[3.3.0]octane-2,4,6,8-tetrone (1) are split in hot ethanol yielding 4, the structure of which was proven by ¹⁵N-NMR spectroscopy. 3,7-Diethyl-(1) and 3-ethyl-(1) show the same behavior. However, the latter yields a mixture of the expected product 12 and 4-ethylpyrazolidine-3,5-dione (13). Under the same conditions, only the unsubstituted ring is split in 3,3-diethyl-(1) leading to 1-ethoxycarbonylacetyl-4,4-diethyl-3,5-pyrazolidinedione (8).