SYNTHESIS OF 9-ARYL-6-CARBAMOYL-1,2-DIHYDROPURINES AND A STUDY OF THEIR TAUTOMERISM
SYNTHESIS OF 9-ARYL-6-CARBAMOYL-1,2-DIHYDROPURINES AND A STUDY OF THEIR TAUTOMERISM
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DOI：
10.1039/p29940001949
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发表时间：
1994-09-01
期刊：
影响因子：
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通讯作者：
PROENCA, MFJRP
中科院分区：
文献类型：
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作者：
ALVES, MJ;BOOTH, BL;PROENCA, MFJRP
通过相应的4-（氰甲酰基）-1 -芳基咪唑-5胺与羰基化合物R(1)R(2)CO (R(1) = R(2) = Me, Et；R(1) = H R(2) = Ph。同样的9-芳基-6-氨基甲酰-1,2-二氢嘌呤(R（1) = R(2) = Me）也通过在碱存在下与丙酮反应从相应的(Z)- n -1-（2-氨基-1,2-二氰乙烯基）- n -2-芳基甲脒中分离得到。在这些情况下，最初形成的产物是灰白色固体，被认为是恶唑烷衍生物4，它们在溶液中迅速转化为各自的1,2-二氢嘌呤。用H-1和C-13核磁共振光谱对二氢嘌呤的两个互变异构体进行了充分的表征，并获得了二氢嘌呤衍生物的橙色和黄色互变异构体的单晶x射线结构，其中Ar = Ph， R(1) = R(2) = Me。在[H-2(6)] Me(2)SO溶液中，n -芳基环上的邻取代基的存在导致黄色互变异构体平衡浓度的增加。Ar = 2,4-(MeO)(2)C6H3时二氢嘌呤单晶x射线结构的测定R(1) = R(2) = Me表明，在固体状态下，芳基环与杂环的平面扭成73.1(9)度，这可以解释在溶液中观察到的行为。
The title compounds have been prepared in high yield by reaction of the corresponding 4-(cyanoformimidoyl)-1 -arylimidazol-5-amines with the carbonyl compounds R(1)R(2)CO (R(1) = R(2) = Me, Et; R(1) = H, R(2) = Ph). The same 9-aryl-6-carbamoyl-1,2-dihydropurines (R(1) = R(2) = Me) have also been isolated from the corresponding (Z)-N-1-(2-amino-1,2-dicyanovinyl)-N-2-arylformamidines by reaction with acetone in the presence of a base. In these cases the initially formed products are off-white solids, believed to be the oxazolidine derivatives 4, which in solution rapidly undergo conversion into the respective 1,2-dihydropurines. The two tautomers of the dihydropurines have been fully characterised by H-1 and C-13 NMR spectroscopy and single-crystal X-ray structures have been obtained for both the orange and yellow tautomers of the dihydropurine derivative where Ar = Ph, R(1) = R(2) = Me. In [H-2(6)] Me(2)SO solution the presence of an ortho-substituent on the N-aryl ring causes an increase in the equilibrium concentration of the yellow tautomer. A single-crystal X-ray structure determination on the dihydropurine where Ar = 2,4-(MeO)(2)C6H3; R(1) = R(2) = Me has shown that in the solid state the aryl ring is twisted at 73.1(9)degrees to the plane of the heterocyclic ring and this may explain the observed behaviour in solution.