Selective synthesis of functionalized thia- and oxacalix[2]arene[2]pyrimidines

Functionalized oxacalix[m]arene[n]pyrimidines have been synthesized by S(N)Ar on 4,6-dihalopyrimidine building blocks. Depending on the S(N)Ar conditions, either a mixture of oxacalix[n]arenes, ranging from oxacalix[4]- up to oxacalix[12]arene, could be prepared or the oxacalix[4]arene could be synthesized selectively in a high yield. The electrophilic (pyrimidine) and the nucleophilic components could both be varied, allowing the preparation of functionalized oxacalix[4]arenes. Moreover, the procedure also gives access to the analogous thiacalix[4]arenes.     

Synthesis of functionalized oxacalix[4]arenes

Tetranitrooxacalix[4]arenes are generated in high yield by the room-temperature S(N)Ar reaction of 1,3-dihydroxybenzenes with 1,5-difluoro-2,4-dinitrobenzene. The reaction is tolerant to a range of functionality on the nucleophilic component, including hydroxyl-substitution at the 2- and 5-positions, which yields previously unknown 26,28- and 5,17-dihydroxyoxacalix[4]arenes.     

Design,structure and anion recognition of larger-rim functionalized oxacalix[2]arene[2]triazine hosts

Larger-rim functionalized tetraoxacalix[2]arene[2]triazine host molecules were efficiently synthesized through a fragment coupling followed by AlCl₃-mediated deprotection/arylation protocol. Substituent effects, functions of counter cations on anion recognition in solution were systematically studied by means of fluorescence and NMR titrations.     

New oxacalix[4]arene carboxylate detects viologen in protic media

ABSTRACT

We demonstrate that Ullman fragment-coupling can be used to synthesise an oxacalix[4]arene monocarboxylic acid, which provides easy access to its water-soluble carboxylato derivatives. Crystallographic and computational data suggest that the new carboxyl-substituted oxacalix[4]arene adopts a 1,3-alternate conformation both in the solid-state and in methanol solution. Its water-soluble tetrabutylammonium derivate can detect the herbicide paraquat at neutral pH in aqueous media (K _a = 111 ± 3 M^–1) and in methanol (K _a = 2020 ± 70 M^–1).     

Syntheses and conformational structures of functionalized tetraoxacalix[2]arene[2]triazines

The syntheses and conformational structures of various functionalized tetraoxacalix[2]arene[2]triazines were studied. Applying the fragment coupling approach and the post-macrocyclization chemical manipulations, a number of tetraoxacalix[2]arene[2]triazines that contain, on the lower rim, one or two aldehyde, ester, carboxylic acid, hydroxymethyl, and aminomethyl functional groups were prepared in moderate to high chemical yields from cheap and commercially available materials. On the basis of X-ray crystallography and NMR spectroscopy, all tetraoxacalix[2]arene[2]triazines containing electron-withdrawing group(s) adopted 1,3-alternate conformation both in solution and in the solid state, while tetraoxacalix[2]arene[2]triazines bearing hydroxymethyl and aminomethyl substituent(s) existed as pinched or distorted partial cone conformers due to the formation of intramolecular hydrogen bond between hydroxyl or amino group and triazine ring.     

Efficient post-macrocyclization functionalizations of oxacalix[2]arene[2]pyrimidines

Diversely functionalized oxacalix[2]arene[2]pyrimidines have been synthesized starting from a bis(methylsulfanyl)-substituted oxacalix[4]arene by two efficient post-macrocyclization pathways. Functionalized aryl groups were introduced on the pyrimidine building block via Liebeskind-Srogl cross-coupling reactions, while a variety of O-, S-, N-, and C-nucleophiles were inserted on the calixarene skeleton by nucleophilic aromatic substitution reactions on the bis(methylsulfonyl)oxacalix[4]arene analogue.     

Synthesis and self-assembly of novel oxacalix[2]arene[2]triazine amphiphiles

Heteracalixaromatics are an emerging generation of macrocyclic host molecules in supramolecular chemistry. As a typical example of heteracalixaromatics, oxacalix[2]arene[2]triazine adopts a shape-persistent 1,3-alternate conformation and can be easily functionalized. Taking it as a platform, a series of oxacalix[2]arene[2]triazine-based amphiphiles bearing long alkyl chains were synthesized through post-macrocyclization functionalization or 3+1 fragment coupling protocols. The self-assembly behavior of these amphiphiles in a mixture of tetrahydrofuran (THF) and water was investigated. Dynamic light scattering (DLS) measurements revealed that the size of the self-assembled aggregates is dependent on the structure of the amphiphiles. The long alkyl chain substituents and/or intermolecular hydrogen bonds were found to promote the self-assembly.     

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.     

系列新型硫杂杯[4]芳烃氮杂衍生物的合成

在对叔丁基硫杂杯[4]芳烃的下缘1,3位引入芳醛基, 合成了硫杂杯[4]二醛基衍生物2. 化合物2与苯胺、水杨酰肼、烟酰肼、异烟酰肼等通过席夫碱缩合反应得到新型硫杂杯[4]氮杂衍生物3a～3d, 产率分别为83%, 80%, 77%和79%. 化合物2与邻苯二胺、乙二酰肼、丙二酰肼、己二酰肼等通过“1＋1”分子间缩合得到新型1,3-桥联硫杂杯[4]氮杂衍生物4a～4d, 产率53%, 51%, 59%和66%. 新化合物的结构经IR, ¹H NMR, MS和元素分析等证实.     

Syntheses of a pillar[4]arene[1]quinone and a difunctionalized pillar[5]arene by partial oxidation

A pillar[4]arene[1]quinone and a difunctionalized pillar[5]arene have been synthesized by partial oxidation.     

Syntheses and conformations of tetrahomodioxacalix[4]arene tetraamides and tetrathioamides

A series of tetrahomodioxacalix[4]arene tetraamides and tetrathioamides with four p-phenyl groups on their upper rim were synthesized. From the (1)H and (13)C NMR and crystal structure, N-butylamido homooxacalix[4]arene (4) was found to be in the 1,3-alternate conformation and has intramolecular hydrogen bonding between N-H and facing oxygen atoms of the carbonyl O=C group. This hydrogen bonding decreased the metal ion complex ability. Transformation of the 1,3-alternate N-butylamido (4) into N-butylthioamido homooxacalix[4]arene (5) using Lawesson's reagent gave a conformational change to the C-1,2-alternate.     

Syntheses and spin-spin exchange interactions of calix[4]arene biradicals

Three novel paramagnetic calix[4]arenes (2, 3 and 4) with two opposite nitroxide radicals on the upper rims were synthesized and characterized. The through-space spin-spin exchange interactions of these calixarene biradicals were investigated, and found to be affected by many factors, such as molecular conformational flexibility, steric hindrance, temperature, solvent effect and complexation of silver ion.     

Synthesis of BINOL-containing oxacalix[4]arenes

Unprecedented chiral oxacalixarenes were obtained from the reaction of (±)-1,1′-binaphthyl-2,2′-diol (BINOL) with 1,5-difluoro-2,4-dinitrobenzene. Structural elucidation of C_2h-symmetric meso (R,S)-oxacalix[4]arene and D₂-symmetric racemic (as well as enantiopure) (R,R)- and (S,S)-oxacalix[4]arene was carried out by means of 1D and 2D NMR spectroscopy, ESI-MS, X-ray diffractometry, and circular dichroism spectroscopy.     

Heck-type olefination and Suzuki coupling reactions using highly efficient oxacalix[4]arene wrapped nanopalladium catalyst

A simple one-pot method is used for the synthesis of water dispersible and stable palladium nanoparticles (PdNps) where oxacalix[4]arene dihydrazide (OXDH) is used as both a reducing and capping agent. The OXDH-PdNps have been characterized by UV–Visible spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDX), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The OXDH-PdNps are spherical in shape with an average size of 3–4?nm and well crystallized in a face centered cubic structure. The capping of the OXDH ligand on the nanoparticles surface was evaluated using FT-IR. The OXDH-PdNps have been used in carbon–carbon coupling reactions, namely, the Suzuki–Miyaura and Mizoroki–Heck reactions. Both of the reactions are carried out under phosphine-free conditions to provide better yields. The nanocatalyst can be easily recovered and reused for six consecutive catalytic cycles without any significant loss in its catalytic activity.     

杯[4]芳烃黄原酸酯衍生物的合成与阳离子萃取性能

以二氧六环作溶剂, 杯[4]芳烃二甲氧基二羟乙氧基衍生物2与氢氧化钾、二硫化碳作用合成了杯芳烃黄原酸盐衍生物3, 并进一步与碘甲烷或氯化苄反应首次合成了含黄原酸酯基的杯芳烃衍生物4a和4b. 阳离子萃取试验表明该新型杯芳烃衍生物比单硫杂杯芳烃衍生物具有更好的过渡金属离子萃取性能.     

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.     

新型多重氮杂杯[4]芳烃衍生物的合成

对叔丁基杯[4]芳烃-1,3-二醛基衍生物1与水杨酰肼、烟酰肼、异烟酰肼反应, 合成了具有开链结构新型杯[4]多重氮杂衍生物2a～2c, 产率分别为88%, 85%和90%. 化合物1与乙二酰肼、丙二酰肼、己二酰肼反应, 得到具有桥联结构的新型杯[4]多重氮杂衍生物3a～3c, 产率分别为86%, 89%和90%. 新化合物的结构经元素分析、质谱、核磁共振谱等表征证实, 杯[4]芳烃单元均为1,3-取代且采取锥式构象.     

杂金属杯[4]配位聚合物的合成与表征

合成了4个杂金属杯[4]配位聚合物{[Cd（L）（tpa）]·3H₂O}_n（1）,{[Zn2（L）₂（tpa）₂]·3H₂O}_n（2）,{[Co（L）（oba）]·2DMA·0.5H₂O}_n（3）和{[Zn（L）（oba）]·DMA}_n（4）（L=2-（1H-咪唑基-甲基）-6-（3-（1H-咪唑基-甲基）-5-叔丁基-2-羟基）苄基-4-叔丁基苯酚,H₂tpa=对苯二甲酸,H₂oba=4,4''-二苯醚二甲酸）,并通过元素分析、热重、红外光谱、固态紫外、单晶X射线衍射和粉末X射线衍射对其进行了表征。单晶结构分析表明晶体1是单斜晶系,P2₁/n空间群,而晶体2,3和4均为三斜晶系,P1空间群。化合物1,2,3和4是由0维[M（N₄O₂C₂₉H₃₆）]（M=Zn,Co,Cd）的杂金属杯[4]与配体对苯二甲酸和4,4''-二苯醚二甲酸形成的一维配位聚合物。     

Syntheses and Crystal Structures of Calix[4]arene Dithiocarbazate Schiff Bases

<正>The regioselective syntheses of novel p-tert-butylcalix[4]arenes with functional aldehyde and dithiocar-bazate Schiff base groups were carried out.p-tert-Butylcalix[4]arene was alkylated with o-,H-(ω-chloroalkoxy)-benzaldehydes in the system of K_2CO_3/KI/CH_3CN to give calixarene 1,3-dialdehydes.Then the condensation reactions of active calixarene aldehydes with S-methyl and S-benzyldithiocarbazate,calixarene sulfur-containing Schiff bases were efficiently obtained in satisfied yields.The single crystal analysis of the four representative products shows that calixarene aldehydes and Schiff bases exist in cone conformation and there are interesting intermolecular hydrogen-bands andπ…πinteraction in the crystals.