Cucurbit[n]uril analogues: synthetic and mechanistic studies.
Cucurbit[n]uril analogues: synthetic and mechanistic studies.
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DOI：
10.1021/jo051655r
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发表时间：
2005-11
期刊：
影响因子：
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通讯作者：
J. Lagona;J. Fettinger;L. Isaacs
中科院分区：
文献类型：
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作者：
J. Lagona;J. Fettinger;L. Isaacs
[反应：见正文]瓜环类似物(18，19，(+/-)-20，33，34，35，36和37)的合成。这些CB[5]、CB[6]和CB[7]类似物都含有并入大环的双(邻苯二甲酰肼)壁。这些CB[n]类似物的特制合成是通过适当的双(亲水性)(4、7或9)与双(邻苯二甲酰肼)(17)缩合来进行的，从而以较高的产率生成CB[6]和CB[7]类似物，而CB[5]类似物以较低的产率形成。为了改善CB[n]类似物在水或有机溶液中的溶解特性，将CO_2Et基团转化为CO_2H和CO_2(CH2)_9CH_3基团。根据产品再提交实验的结果，我们得出结论，这些大循环是动力学产物。为了使CB[6]和CB[7]模拟大环化反应中获得的良好产率合理化，我们对模型亚甲基桥联甘脲二聚体进行了机理研究，这表明在CB[n]类似物形成过程中会发生分子内异构化。
[reaction: see text] The synthesis of cucurbit[n]uril analogues (18, 19, (+/-)-20, 33, 34, 35, 36, and 37) is presented. These CB[5], CB[6], and CB[7] analogues all contain bis(phthalhydrazide) walls that are incorporated into the macrocycle. The tailor-made synthesis of these CB[n] analogues proceeds by the condensation of the appropriate bis(electrophile) (4, 7, or 9) with bis(phthalhydrazide) (17), which delivers the CB[6] and CB[7] analogues in good yield, whereas the CB[5] analogue is formed in low yield. To improve the solubility characteristics of the CB[n] analogues for recognition studies in water or organic solution, the CO2Et groups were transformed to CO2H and CO2(CH2)9CH3 groups. On the basis of the results of product resubmission experiments, we conclude that these macrocycles are kinetic products. To help rationalize the good yields obtained in the CB[6] and CB[7] analogue macrocyclization reactions, we performed mechanistic studies of model methylene bridged glycoluril dimers, which suggest an intramolecular isomerization during CB[n] analogue formation.