Synthesis of new calix[4]pyrrole derivatives via 1,3-dipolar cycloadditions

Octamethylcalix[4]pyrrole-2-carbaldehyde 1 and 3-(octamethylcalix[4]pyrrol-2-yl)propenal 5 were used as precursors of azomethine ylides, which were trapped in situ with a range of dipolarophiles, such as 1,4-benzoquinone, 1,4-naphthoquinone, and fumaronitrile. Aldehyde 1 showed very low reactivity but the azomethine ylide generated from the reaction of aldehyde 5 with N-methylglycine could be trapped with those dipolarophiles to afford new β-substituted octamethylcalix[4]pyrrole derivatives in moderate yields. The resulting cycloadducts show high affinity constants for fluoride and acetate anions; compounds 7 and 8 display sharp changes in color in the presence of these anions.     

Synthesis and Complexation Properties of Novel Chiral Calix[4]-1,3-aza-crown and Calix[4]arene Hydrazone Derivative

<正>Refluxing calix[4]-1,3-substituted benzaldehyde derivative(4) with glycine hydrazide derivative,we obtained a novel calix[4]arene hydrazone derivative(5) via"1+2"condensation in a yield of 78%.In the reaction of compound 4 with L-leucine hydrazide derivative at room temperature,lariat calix[4]-1,3-aza-crown(6) with chiral amino acid group as branched chain was synthesized via"1+1"addition in a yield of 70%.The preliminary extraction experiments suggested that hosting compounds 5 and 6 possessed good complexation abilities forα-amino acids.     

Synthesis and cations complexation of dumbbell shaped biscalix[4]-1,3-aza-crown with rigid thiourea-bridge

By reacting calix[4]-1,3-aza-crown 2 with 1,4-phenyl diisothiocyanate in “1 + 2” condensation mode, the novel dumbbell shaped biscalix[4]-1,3-aza-crown 3 with rigid thiourea-bridge was conveniently prepared in yield of 85%. Its structure and conformation were characterized by elemental analyses, ESI-MS, ¹H NMR and ¹H–¹H COSY techniques. The complexation properties of compound 3 were investigated by liquid–liquid extraction experiments and ¹H NMR titration experiments. The results showed that compound 3 has excellent complexation abilities for soft cations and outstanding extraction selectivity for Ag⁺. The Ag⁺/Na⁺ and Ag⁺/Hg²⁺ extraction percentage of host 7 were as high as 43.2 and 16.9, respectively. ¹H NMR titration experiments revealed the 1:2 stoichiometry of receptor 3-Ag⁺ complex was formed.     

Synthesis and amino acid extraction abilities of chiral calix[4]arene triamides containing amino alcohol units

Herein the synthesis and extraction abilities of new d-/l-phenylalaninol substituted p-tert-butylcalix[4]arene triamide derivatives (3 and 4) towards amino acids are reported. These compounds (3 and 4) have been easily synthesized via aminolysis of p-tert-butylcalix[4]arene trimethylester (2) with d-/l-phenylalaninol in methanol-toluen solvent system at one step. The extraction properties of the prepared chiral calix[4]arene triamide derivatives (3 and 4) towards some selected amino acid methylesters are studied by liquid–liquid extraction. Results show that these chiral calix[4]arene triamide derivatives (3 and 4) exhibited a good affinity towards all amino acid species without any remarkably discrimination.     

Synthesis and anti-integrase evaluation of novel calix[4]arene derivatives containing the triazolyl 1,3-diketo moiety

A series of novel calix[4]arene derivatives incorporating two triazolyl 1 3-diketo subunits in alternate positions at the lower rim were synthesized and screened for HⅣ integrase inhibition activity.The chemical structures of these compounds were confirmed by means of1H NMR 13C NMR,and ESI-MS.Preliminary bioassays indicated that calix[4]arene derivatives proved to be more active than p-tertbutylcalix[4]arene derivatives.In particular,compound 4g presented the most potent integrase strand transfer inhibitory activity with an IC50value of 6.1 mmol/L.     

Synthesis of two calix[4]arene diamide derivatives for extraction of chromium(VI)

The synthesis of four diamide derivatives of the p-tert-butylcalix[4]arenes from the reaction of 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dihydroxycalix[4]arene 2 with various primary amines were reported. The ¹H and ¹³C NMR, data showed that the synthesized compounds exist in the cone conformation. The complexing properties of these compounds toward Cr₂O₇²⁻/HCr₂O₇⁻ anions are also studied. It has been observed that receptors 5 and 6 are better extractant than the compounds 3 and 4. The protonated alkyl ammonium form of 5 and 6 is an effective extractant for transferring HCr₂O₇⁻/Cr₂O₇²⁻ anions from an aqueous phase into a dichloromethane layer.     

Syntheses and extraction properties of novel biscalixarene and thiacalix[4]arene hydrazone derivatives

By reacting thiacalix[4]arene with p-tosyloxyethoxylbenzaldehyde 1, 3-bis(benzaldehyde-4-oxyethyloxy)-p-tert-butylthiacalix[4]arene (2) were prepared in yield of 65%. Refluxing compound 2 with aniline, salicylic hydrazide, nicotinic hydrazide and isonicotinic hydrazide, novel ringopening 1,3-bis-arylformyl-hydrazone substituted thiacalix[4]arene derivatives (3a–3d) were obtained in yields of 77–89%. Refluxing compound 2 with o-phenylendiamine, oxalyl dihydrazide, malonic dihydrazide and adipic dihydrazide in “1 + 1” intermolecular condensation mode under diluted condition, novel 1,3-bis-acyl hydrazone-bridged calix[4]arene derivatives (4a–4d) were prepared in good yields. Moreover, by condensating compound 2 with 1,3-bis(hydrazinocarbonyl-methoxy)-p-tert-butylcalix[4]arene (5), the first example of hydrazone-bridged biscalixarene (6) with calix[4]arene and thiacalix[4]arene subunits was facilely synthesized in yield of 90%. The noncompetitive and competitive extracting experiments showed that these novel hosts were good receptors for both metal cations and α-amino acids. Compounds 3a–3d and 4a–4d showed similar binding properties with high extraction percentage but low extracting selectivities. Biscalixarene 6 exhibited not only high extracting abilities but also good extracting selectivities.     

杯[4]芳烃单取代1,3-二酮衍生物的合成及生物活性研究

以杯[4]芳烃为原料经醚化和克莱森缩合两步反应首次合成杯[4]芳烃单取代1,3-二酮衍生物,其结构经1H NMR、13C NMR及MS表征。初步的HIV-1整合酶链转移反应活性测试结果表明,该杯[4]芳烃单取代1,3-二酮衍生物在测试浓度为25μM时其抑制率为12.67%。     

Hydrophosphinoyl derivatives of calix[4]resorcinarenes

Calix[4]resorcinarene reacts with N,N,N",N"-tetraethyl-P-ethylphosphonous diamide to give dioxaphosphocines, whose hydrolysis with intracavity water yields phosphinoyl derivative of calix[4]resorcinarene.     

Synthesis and extraction studies of polymeric phthalimido functionalized calix[4]arene

The article comprises synthesis and extraction studies of polymeric calix[4]arene having phthalimide groups at the lower rim. The polymeric phthalimido functionalized calix[4]arene was synthesized via radical initiated reactions involving a vinylic monomer 5,11,17,23-tetra-tert-butyl-25-[4-(acrylamido)benzyloxy]-26,28-bis-(2-phthalimido-ethoxy)-27-hydroxycalix[4]arene (5) with styrene. A five atom spacer group was incorporated between the bulky calixarene core and the acrylate moiety in order to minimize steric interactions which proved to impede the polymerization. From the liquid–liquid and solid–liquid extraction studies it has been concluded that the precursor 3 (5,11,17,23-tetra-tert-butyl-25-(4-nitro benzyloxy)-26,28-bis-(3-phthalimidoethoxy)-27-hydroxy-calix[4]arene) is selective for metal cations. The order of extractability of metal cations by the ligand 3 decreases in the sequence: Hg²⁺ > Cd²⁺ > Cu²⁺ > K⁺ > Co²⁺ whereas its polymeric derivative is selective in the sequence: Hg²⁺ > Cd²⁺ > K⁺ > Co²⁺ > Cu²⁺ for the metal cations used in the experiments.     

A new Hg-selective fluorescent sensor based on a dansyl amide-armed calix[4]-aza-crown

A new fluorescent chemosensor for Hg²⁺ based on a dansyl amide-armed calix[4]-aza-crown was reported. It exhibits high sensitivity and selectivity toward Hg²⁺ over a wide range of metal ions in MeCN-H₂O (4:1, v/v). The association constant of the 1:1 complex formation for 2-Hg²⁺ was calculated to be 1.31 × 10⁵ M⁻¹, and the detection limit for Hg²⁺ was found to be 4.1 × 10⁻⁶ mol L⁻¹.     

Synthesis of mono- and 1,3-diaminocalix[4]arenes via Ullmann-type amination and amidation of 1,3-bistriflate esters of calix[4]arenes

Practical methods are described for the preparation of monoamines 4 and 1,3-diamines 5, bearing one or two amino group(s) instead of the hydroxy group(s) at the 28-position or at both the 26- and 28-positions of p-tert-butylcalix[4]arene (1a) and p-tert-butylthiacalix[4]arene (1b), via the Ullmann-type amination or amidation. Thus, the copper-catalyzed or mediated amination of the 1,3-bistriflate ester (2a) of 1a with benzylamine affords either mono(benzylamino) triflate 7a or 1,3-bis(benzylamine) 8 in a high yield, depending on the reaction conditions. On the other hand, the 1,3-bistriflate ester (2b) of 1b resists disubstitution and produces, under stoichiometric conditions, mono(benzylamino) triflate 7b. The disubstitution of 2b is achieved by amidation with tosylamide, giving 1,3-bis(tosylamide) 17b. The hydrogenolysis of the benzylamino moiety of 7a, followed by the hydrolysis of the Tf moiety, affords monoamine 4a, while the hydrogenolysis of 8 affords 1,3-diamine 5a. The amino moiety of 7b can be deprotected under acidic conditions to give, after hydrolysis, monoamine 4b. The hydrolysis of 17b affords 1,3-diamine 5b. The overall yields of compounds 4a, 4b, 5a, and 5b are 72%, 45%, 78%, and 24%, respectively, based on commercially available compounds 1 and are much higher than the ones previously reported in the literature.     

The synthesis and anions complexation property of novel biscalixarene: dumbbell shaped biscalix[4]-1,3-aza-crown

By reacting calix[4]-1,3-aza-crown 2 with 1,6-diisocyanatohexane in “1+2” condensation mode, the first example dumbbell shaped biscalix[4]-1,3-aza-crown 3 was conveniently prepared in yield of 94%. The complexation properties of compound 3 were investigated by UV–vis spectra and ¹H NMR experiments. The results showed that compound 3 has good complexation abilities for anions. Compound 3 binded monoacidic anions with 1:2 binding-stoichiometry and binded binary acidic anions with 1:1 binding-stoichiometry.     

Dendritic octa-CMPO derivatives of calix[4]arenes

Calix[4]arenes substituted at the narrow or wide rim by eight carbamoylmethyl-phosphine oxide (CMPO) functions in a dendritic manner were synthesised and studied in extraction of Eu³⁺ and Am³⁺ from aqueous nitric acid into o-nitrophenylhexyl ether. ¹H NMR relaxivity titrations for a wide rim octa-CMPO reveal the clear formation of a solvent-free 1:2 ligand/metal complex, while the wide rim tetra-CMPO formed oligomeric complexes under similar conditions.     

Synthesis and fluorescence sensing properties of novel pyrene-armed calix[4]arene derivatives

Fluorogenic tert-butylcalix[4]arenes bearing two pyrene pendant groups at the lower rim were synthesized. Based on ratiometric changes of monomer and excimer emissions, the pyrene amine derivative of calix[4]arene has been found to act as a selective sensor for Pb²⁺ and Cu²⁺ ions, respectively, due to a conformational change upon chelation of these ions.     

新型杯[4]芳烃衍生物的合成及其氨基酸萃取性能

杯[4]-1,3-二乙酸乙酯衍生物(1)与水合肼反应生成杯[4]芳烃酰肼衍生物(2),化合物(2)与异硫氰酸苯酯反应得到含酰胺和硫脲单元的新型杯[4]芳烃衍生物(3).总产率达70%.系列氨基酸萃取实验表明化合物(3)对异亮氨酸有较好的选择性萃取能力.     

Electrochemical investigation of nano-baskets of calix[4]-1,3-crowns-5,6 complexes

Four nano-baskets of calixarene including cone 25,27-di(carboxymethoxy)calix[4]arene-crown-5, 1,3-alternate 25,27-di[carboxymethoxy]-calix[4]arene-crown-5, cone 25,27-bis[carboxymethoxy]calix[4]arene-crown-6 and 1,3-alternate 25,27-di[carboxymethoxy]-calix[4]arene-crown-6 were synthesized and their binding abilities towards alkali and alkaline earth metals as well as some lanthanides were studied using differential pulse voltammetry. The novelty of this study was investigation of those macrocyclic complexes by voltammetric behaviors of two acidic moieties in each scaffold during complexation of crown ether ring. Their voltammetric behaviors were closely related to the complex formation by entrapment of cation into crown ether cavity and ion–dipole interaction between cation and acidic moieties in calixcrowns. The results revealed the selective changes in voltammetric behavior of synthesized scaffolds toward the cations. Moreover, the position of crown ether in 1,3-alternate instead of cone enhanced the domain of binding ability to more cations. Furthermore, it was shown that those carboxylic acid moieties, which were far from the crown ether ring in the 1,3-alternate, did not affected by encapsulated cations in the coordination space of crown ether and showed no voltammetric behavior.     

Synthesis and electrochemical properties of calix[4]arene derivatives containing ferrocene units in the cone and 1,3-alternate conformation

Two novel calix[4]arene receptors containing ferrocene units in cone (L₁) and 1,3-alternate (L₂) conformations have been synthesized from 25,27-dihydroxy-26,28-bis[(3-aminopropyl)oxy]calix[4]arene 4 or 25,26,27,28-tetra[(3-aminopropyl)oxy]calix[4]arene 6 and ferrocenecarboxaldehyde via condensation, respectively. Their structures have been characterized by ¹H, ¹³C, APT, COSY NMR, FTIR, HSMR, and UV–vis spectral data. The electrochemical behavior of L₁ and L₂ has been investigated in the presence of F^?, Cl^?, Br^?, H₂PO₄^?, CH₃COO^? anions. Electrochemical studies show that these receptors electrochemically recognize CH₃COO^?, H₂PO₄^?, and Cl^?, anions. Using an UV–vis study, the selectivity to these anions in DMSO solution was confirmed.     

Stilbene-bridged 1,3-alternate calix[4]arene crown ether for selective alkali ion extraction

A series of stilbene-bridged calix[4]arenes was synthesized through an intramolecular reductive McMurry coupling of bisbenzaldehyde calix[4]arene in high yields. Tetra- and pentaethylene glycol chains were tethered to the phenolic groups of calix[4]arene to form stilbene-bridged calix[4]arene crown-5 and crown-6, respectively. The presence of stilbene bridge over the calix[4]arene rim effectively prevented the connection of the polyether chains in the cone conformation resulting in the exclusive formation of 1,3-alternate stilbene-bridged calix[4]arene crown product. Compared to the cone analogues, the 1,3-alternate calix[4]arene crown ethers showed a greater extraction ability and selectivity toward Cs⁺.     

Synthesis and self-assembly of novel calix[4]arenocrowns: formation of calix[4]areno[2]catenanes

A series of novel calix[4]arenocrowns 1a-c were efficiently synthesized by a one-pot reaction of calix[4]monohydroquinone diacetate 5 with ditosylate 6 and its analogues in the presence of sodium hydroxide. It was found that the calix[4]arenocrowns could form stable pseudorotaxane-type complexes 2a-c with paraquat, and further self-assemble into calix[4]areno[2]catenanes 3a-c with dicationic salt 8 and p-bis(bromomethyl)benzene.