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首页> 外文期刊>The Journal of Organic Chemistry >Preparation and Conformation of Monohalotetrahydroxycalix[5]arenes
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Preparation and Conformation of Monohalotetrahydroxycalix[5]arenes

机译：一卤代四羟基杯[5]芳烃的制备与构型

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The intraannular introduction of a halogen into a calixarene skeleton is described. Monoaminotet-rahydroxy-p-tert-butylcalix[5]arene (2b) was diazotized by treatment with isoamyl nitrite/HCl/EtOH. Thermal dediazoniation of the salt in chloroform yielded monochlorotetrahydroxy-p-tert-butylcalix-[5]arene (5a) and the xanthenocalix[5]arene 6. These products result from the capture of an intermediate phenyl cation derivative by chloride ion or intramolecularly, by a neighboring phenol ring. The product ratio 6:5a was not affected by the addition of excess external chloride, suggesting that the reacting intermediate exists as an ion pair. The dediazoniation reaction in the presence of bromide and iodide ions afforded the corresponding halocalixarenes 5b and 5c, while in the presence of a fluoride ion the calixindazole 8 was obtained. X-ray diffraction indicates that 5b exists in a distorted cone conformation (cone-in) in which the extraannular edge of the halophenyl ring is tilted toward the cavity center. The halocalixarenes undergo a cone-to-cone inversion process with a barrier in the 11.3-12.5 kcal mol~(-1) range in CDCl_3. The barrier height is a function of the size of the halo substituent. Xanthenocalix[5]arene 6 crystallizes with three ethanol solvent molecules and exists in a cone-like conformation.
机译：描述了卤素向杯芳烃骨架内的环内引入。通过用亚硝酸异戊酯/ HCl / EtOH处理将单氨基叔戊基-对羟基-对叔丁基杯[5]芳烃（2b）重氮化。盐在氯仿中的热脱氮反应生成一氯四羟基-对叔丁基杯杯[5]芳烃（5a）和黄苯并[5]芳烃6。这些产物是由氯离子或分子内捕获中间苯基阳离子衍生物形成的，通过相邻的苯酚环。产物比例6：5a不受添加过量外部氯化物的影响，表明反应中间体以离子对形式存在。在溴离子和碘离子的存在下进行的重氮化反应得到了相应的卤代芳烃5b和5c，而在氟离子的存在下得到了杯辛达唑8。 X射线衍射表明5b以扭曲的圆锥构型（con-in）存在，其中卤代苯环的环形外边缘向腔中心倾斜。卤代芳烃经过锥锥转化，其势垒在CDCl_3中为11.3-12.5 kcal mol〜（-1）。势垒高度是卤素取代基的大小的函数。 Xanthenocalix [5] arene 6与三个乙醇溶剂分子一起结晶，并以圆锥状构象存在。

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