Controlling factors in the synthesis of cucurbituril and its homologues.
TL;DR: A wide range of reaction conditions are examined that include the effects of acid type, acid concentration, reactant concentrations, and temperature to both probe the mechanism and optimize the yields of isolated cucurbit[n]urils, where n = 5-10.
Abstract: The acid-catalyzed synthesis of cucurbit[n]urils from formaldehyde and glycoluril is poorly understood. In this paper, we examine a wide range of reaction conditions that include the effects of acid type, acid concentration, reactant concentrations, and temperature to both probe the mechanism and optimize the yields of isolated cucurbit[n]urils, where n = 5−10. A mechanism for the formation of these cucurbit[n]urils is presented. Individual cucurbit[n]urils were unambiguously identified in reaction mixtures using ESMS and 13C NMR.
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TL;DR: In 1981, the macrocyclic methylene-bridged glycoluril hexamer (CB[6]) was dubbed "cucurbituril" by Mock and co-workers because of its resemblance to the most prominent member of the cucurbitaceae family of plants--the pumpkin.
Abstract: In 1981, the macrocyclic methylene-bridged glycoluril hexamer (CB[6]) was dubbed "cucurbituril" by Mock and co-workers because of its resemblance to the most prominent member of the cucurbitaceae family of plants--the pumpkin. In the intervening years, the fundamental binding properties of CB[6]-high affinity, highly selective, and constrictive binding interactions--have been delineated by the pioneering work of the research groups of Mock, Kim, and Buschmann, and has led to their applications in waste-water remediation, as artificial enzymes, and as molecular switches. More recently, the cucurbit[n]uril family has grown to include homologues (CB[5]-CB[10]), derivatives, congeners, and analogues whose sizes span and exceed the range available with the alpha-, beta-, and gamma-cyclodextrins. Their shapes, solubility, and chemical functionality may now be tailored by synthetic chemistry to play a central role in molecular recognition, self-assembly, and nanotechnology. This Review focuses on the synthesis, recognition properties, and applications of these unique macrocycles.
2,074 citations
TL;DR: This Account is a compilation of recent literature covering the syntheses of the homologues and derivatives, and their supramolecular chemistry of cucurbituril, a synthetic receptor.
Abstract: The supramolecular chemistry of cucurbituril, a synthetic receptor, is fascinating because of the remarkable guest binding behavior of the host. Studies in the field, however, have met with limitations, since the only species known was the hexameric macrocyclic compound, cucurbit[6]uril. Recently we synthesized its homologues, cucurbit[n]uril (n = 5, 7, 8), and derivatives. These new members of the cucurbituril family have expanded the scope further, and interest in them has grown enormously. This Account is a compilation of recent literature covering the syntheses of the homologues and derivatives, and their supramolecular chemistry.
1,544 citations
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TL;DR: The fundamental properties of CBn homologues and their cyclic derivatives are discussed with a focus on their synthesis and their applications in catalysis.
Abstract: In the wide area of supramolecular chemistry, cucurbit[n]urils (CBn) present themselves as a young family of molecular containers, able to form stable complexes with various guests, including drug molecules, amino acids and peptides, saccharides, dyes, hydrocarbons, perfluorinated hydrocarbons, and even high molecular weight guests such as proteins (e.g., human insulin). Since the discovery of the first CBn, CB6, the field has seen tremendous growth with respect to the synthesis of new homologues and derivatives, the discovery of record binding affinities of guest molecules in their hydrophobic cavity, and associated applications ranging from sensing to drug delivery. In this review, we discuss in detail the fundamental properties of CBn homologues and their cyclic derivatives with a focus on their synthesis and their applications in catalysis.
960 citations
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404 citations
TL;DR: Synthese de la chaine du taxol a partir du phenylacetylene avec comme etapes-cle une epoxydation asymetrique et la scission regioselective de l'epoxyde as mentioned in this paper.
Abstract: Synthese de la chaine du taxol a partir du phenylacetylene avec comme etapes-cle une epoxydation asymetrique et la scission regioselective de l'epoxyde
203 citations
TL;DR: The complex formation of the ligand cucurbituril with alkaline cations and other cations have been studied by means of solubility measurements in the presence of the salts in aqueous solutions at 25 °C.
136 citations
TL;DR: In this article, the existence of two different complexes of cucurbituril with 4-methylbenzylammonium ions was reported. But the 1 : 1 stability constants were not reported for the 2 : 1 complexes with different cations.
Abstract: Kinetic measurements indicate the existence of two different complexes of cucurbituril with 4-methylbenzylammonium ions: (i) an association complex, where the ammonium group binds to one of the polar portals of cucurbituril and the hydrophobic part extends into the solvent, and (ii) an inclusion complex, where the hydrophobic part extends into the cavity of cucurbituril. This complex is used as an indicator for the binding of simple monovalent cations to cucurbituril. Stability constants are reported for the 1 : 1 complexes of cucurbituril with different cations.
122 citations