Shaping calix[8]arene framework by intramolecular bridging. Synthesis of conformationally blocked calix[8]arene derivatives
作者:Francesca Cunsolo、Mario Piattelli、Placido Neri
DOI:10.1039/c39940001917
日期:——
The first examples of 1,5-intrabridged calix[8]arene derivatives are described, which are conformationally frozen in a double-conical shape suitable for ditopical recognition.
描述了1,5-内桥杯[8]芳烃衍生物的第一个实例,其构象冻结为适合圆锥形识别的双圆锥形状。
Alkylation Products of a Calix[8]arene Trianion. Effect of Charge Redistribution in Intermediates
作者:Placido Neri、Grazia M. L. Consoli、Francesca Cunsolo、Concetta Rocco、Mario Piattelli
DOI:10.1021/jo970029u
日期:1997.6.1
well-defined calix[8]arene trianion under alkylation conditions was investigated by reacting the tetraethylammonium salt of p-tert-butylcalix[8]arene trianion with p-methylbenzyl bromide. Chromatography of the reaction mixture afforded the following derivatives in order of decreasing yields: 1,3,5,7-tetrakis-, 1,3-bis-, 1,3,5-tris-, 1,2,4-tris-, and mono(p-methylbenzyl)-p-tert-butylcalix[8]arene, besides
macrocycle. In the light of this result, a reinvestigation of methylation of p-tert-butylcalix[8]arene (1) promoted by weak bases was undertaken. In order to overcome insolubility problems, the crude reaction mixture was subjected to exhaustive benzylation that yielded the soluble mixed methyl-benzyl ethers. It was thus evidenced that direct 1,3,5,7-tetramethylation occurs and this clarifies the apparently “anomalous”
Preorganization of calix[8]arenes. Synthesis of basket-shaped doubly-crowned calix[8]arenes
作者:Corrada Geraci、Mario Piattelli、Placido Neri
DOI:10.1016/0040-4039(95)00997-q
日期:1995.7
The first calix[8]crowns, 3 and 4, frozen in a basket-shaped conformation, have been obtained by reaction of 1,3,5,7-tetrakis(p-tert-butylbenzyl) ether of p-tert-butylcalix[8]arene with tetraethylenglycol ditosylate. Their structure was deduced from mass (FAB) and NMR spectra and the conformational features have been studied by VT NMR. The 1,5-3,7-bis-crown 4, in which one of the ether chains fills