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the reaction leads to ring opening. We have succeeded in preparing (2) by direct reaction of 4-amino-5-dimethoxymethylpyrimidine ( 1 ) I21 with s-triazine. Compound (2) is very sensitive toward water. Its structure has been proved by elemental analysis and by IR and N M R spectroscopy. The N M R signals [8 = 9.91 (H2 and H7), 6 i 9.76 (H4 and H7)] are shifted to lower field strengths than those of pyrimidine.
2.5 g (15 mmoles) of 3-amino-5-dimethoxymethylpyrimidine and 1.2 g (1 5 mmoles) of s-triazine are intimately mixed by grinding in a dish-shaped mortar in the absence of moisture. The mixture is then heated to 130 O C (oil bath temperature) in an atmosphere of highly pure nitrogen over a period of 90 minutes. The product is immediately sublimed from the reac-tion mixture at llOยฐC (oil bath temperature) and 0.05 torr. 0.8 gofcrudeproduct, m.p. 90-135 O C (decornp.), isobtained, which, after recrystallization from anhydrous benzene or anhydrous tetrahydrofuran. affords 0.3 g of pure (2) [m.p.
193 "C (decomp.); yield 15 73.
๐ SIMILAR VOLUMES
Excluding cyclopentadienone as an intermediate in the thermolysis of (3) we feel that the difference in thermolytic fragmentation of 0-and p-benzoquinone can be explained by assuming that primarily a cyclopropanone-type intermediate is formed in the case of p-benzoquinone. Bicyclo-[2.1.0]pent-4-en-2
The whole is then left standing for 1 --2 days at O O C . Alkaline alcoholic solutions vacuum sublimation of the residue left after evaporation of the ether from the extract. Compound (2c) is isolated as its picrate, made by boiling the (3-dicarbonyl compound with picric acid in ethanol. COOCrH5 COO