STEREOCHEMICAL STUDIES 107; SATURATED HETEROCYCLES 111; PREPARATION OF URACILS VIA CYCLOREVERSION OF NORBORNENE-FUSED PYRIMIDINEDIONES

Article abstract of DOI:10.1016/S0040-4020(01)81504-0

From diexo-norbornane- and norbornene-azetidinones 5 and 6 with aryl isocyanates, N-arylcarbamoyl-substituted β-lactams (9 and 10) were prepared.The structures of the compounds were elucidated by IR, NMR spectroscopy and X-ray analysis, in comparison with saturated methylene-bridged quinazoline-2,4-diones (7a-b) prepared from norbornane-diexo-β-amino acid (1) with isocyanates and PPA.When heated with PPA, compounds 9 can be isomerized to 7.For preparation of the unsaturated compounds 8, the amino acid 2 was converted into the acid amides (13) and cyclized with 1,1'-carbonyl-diimidazole to tricyclic quinazoline-2,4-dione (8a-e), which decompose when heated, splitting off cyclopentadiene to yield 3-substituted uracils (14).