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Ouro-Sama Adetchessi 《Tetrahedron》2005,61(18):4453-4460
2-Substituted-4a-hydroxy-9H-cycloalkyl[1,2-e]oxazolo[3,2-a]pyrimidin-9-ones 2a-c were synthesized by an one-step cyclocondensation from the 5-substituted-2-amino-2-oxazolines 1a-c with ethyl 2-oxocyclohexanecarboxylate in ethanol at room temperature, and easily dehydrated to provide 2-substituted-9H-cycloalkyl[1,2-e]oxazolo[3,2-a]pyrimidin-9-ones 3. In refluxing xylene, the reaction conducted with various ethyl 2-oxocycloalkanecarboxylates led to the two isomeric 2-substituted-8/9H-cycloalkyl[1,2-e]oxazolo[3,2-a]pyrimidin-8/9-ones 3 and 2-substituted-5H-cycloalkyl[1,2-d]oxazolo[3,2-a]pyrimidin-5-ones 4. The structure of some compounds was unambiguously established using X-ray crystallography. According to results from the DSC analysis of compound 2a, formation of the thermodynamically stable pyrimidinones 4 could be related to an intramolecular rearrangement of kinetically controlled pyrimidinones 3. 相似文献
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Ouro Adetchessi Daniel Desor Isabelle Forfar Christian Jarry Jean Michel Leger Michel Laguerre Alain Carpy 《Journal of heterocyclic chemistry》1997,34(2):429-434
The reaction of 2-amino-2-oxazolines with ethoxycarbonyl isocyanate was investigated in order to access to fused 1,3,5-triazine-2,4-diones with a potential 5-HT2 antagonist activity. The reaction leads to 2,3,6,7-tetrahydro-4H-oxazolo[3,2-a]-1,3,5-triazine-2,4-diones and to 1-carbethoxy-3-(2-iminooxazolidine)ureas. During the carbamoylation the regioselectivity seems to be related to the strong nucleophilic character of the endo nitrogen atom of 2-amino-2-oxazolines. The structures of two compounds were studied by X-ray crystallography. N-Substituted compounds have been prepared by alkylation of the 2,3,6,7-tetrahydro-7-phenoxymethyl-4H-oxazolo[3,2-a]-1,3,5-triazine-2,4-dione. 相似文献
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