Synthesis And Supramolecular Properties Of Glycoside Urea Modified Semi-cucurbitacin Derivative

Novel macrocyclic compounds are research hotspots in the field of supramolecular chemistry.Cucurbit[n]urils,as an important class of macrocyclic compounds,were discovered by German chemist Behrend in 1905.Cucurbit[n]urils have highly symmetrical hydrophobic cavities and two polar ports composed of carbonyl groups.This structure makes it have good performance in accommodating guest molecules.Although cucurbit[n]urils exhibit excellent host-guest properties,their poor solubility and difficult functionalization hinder their application and development to a certain extent.Therefore,chemists from various countries are committed to exploring the synthesis of a series of functionalized cucurbit[n]uril derivatives.In these studies,Miyahara reported the synthesis of cucurbit[n]urils in2004.Compared with the characteristics that cucurbit[n]urils can only be dissolved in acids,hemicucurbiturils can be dissolved in organic solvents such as alcohols and chloroform.Since the discovery of hemicucurbiturils,researchers from various countries have also made a series of derivatives of hemicucurbiturils,but most of the modified hemicucurbiturils were carried out on the ethyl group of the ethyleneurea unit,and the ethyleneurea unit was not replaced.In this paper,the synthesis method of a new type of modified hemicucurbiturils constructed by the mixture of derived glycoluril,ethyleneurea and benzene ring was optimized and adjusted.Two new modified hemicucurbiturils structures were further synthesized from the prepared modified hemicucurbiturils,and the supramolecular chemical properties of the macrocyclic compounds containing hydantoin structure were preliminarily explored.This paper will be composed of the following parts:(1)Synthesis optimization of modified hemicucurbiturils involving derivative glycoluril and aromatic groupsThrough the synthesis of the derived glycoluril unit,the corresponding fragment was constructed with m-dichlorobenzyl and ethyleneurea.The reaction conditions were screened and the route was improved.The method of synthesizing modified hemicucurbiturils containing glycoluril structure was adjusted and optimized,and the corresponding method was obtained.(2)Study on the synthesis of new macrocyclic compounds by glycoluril modified hemicucurbiturilsThe deprotection method of hemicucurbiturils modified with PMB was investigated.Through the screening of reaction conditions,the derivative hemicucurbiturils containing glycoluril,ethyleneurea and aromatic group without PMB was obtained.The binding site on the new cyclic glycoluril can support the follow-up study of various derivative hemicucurbiturils.In the process of removing the PMB protecting group,a new macrocyclic compound containing hydantoin structure was obtained.(3)Preliminary study on the host-guest properties of modified hemicucurbiturils containing hydantoin structureThe interaction between hemicucurbiturils containing hydantoin structure and hydroquinone:By means of nuclear magnetic titration,we investigated the interaction between the three guest molecules of o-,m-,and hydroquinone and the host-guest interaction of the derived hemicucurbiturilsl.The corresponding stability constants were obtained by ITC(isothermal calorimetry titration).According to nuclear magnetic titration and ITC,the difference between the derivative hemicucurbiturils and the three guests was compared.The interaction between hemicucurbiturils containing hydantoin structure and halogen anions:The host-guest interaction between F~-,Cl~-,Br~-,I~-anions and derived hemicucurbiturils was investigated by NMR titration.The binding ratios of the four anions to the derived hemicucurbiturils were obtained by Job method,and the corresponding stability constants were calculated according to the molar ratio method.