An Efficient Aerobic Oxidation for p-Xylene to p-Toluic Acid using Azacrown Ether-tethered Mn(III) Schiff Base Complexes as Catalysts

The oxidation of p-xylene to p-toluic acid with air at 110°C under normal atmospheric pressure occurs efficiently in the presence of crown Mn(III) Schiff base complexes [Formula: See Text] (n=1-4). Significant conversion levels (up to 75%) and selectivity (up to 92-96%) are obtained; the effect of the azacrown ether pendants in Mn(III) Schiff base complexes on the oxidation of p-xylene are also investigated by comparison with the crown-free analogues [Formula: See Text] Moreover, addition of alkali metal ions accelerates the rate of conversion of p-xylene to p-toluic acid.     

Effect of solvent upon competitive liquid-liquid extraction of alkali metal cations by isomeric dibenzo-16-crown-5-oxyacetic acids

The selectivity and efficiency of competitive liquid-liquid extraction of alkali metal cations into organic solvents containingsym-(octyl)dibenzo-16-crown-5-oxyacetic acid (2) andsym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid (3) have been determined. Solvents examined include: dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene,p-xylene, chlorobenzene, 1,2-dichlorobenzene, and 1,2,3,4-tetrahydronaphthalene. The Na⁺/K⁺ and Na⁺/Li⁺ extraction ratios are highest in chloroform. The extraction selectivity is found to correlate with the diluent parameter (DP) of the organic solvent.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Design and Synthesis of New Chiral Calix[4]arenes as Liquid Phase Extraction Agents for α-Amino Acid Methylesters and Chiral α-Amines

The article describes the synthesis and extraction properties of new (S)-(-)-1-phenylethylamine substituted p-tert-butylcalix[4]arene/calix[4]arene. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4a), or 5,11,17,23-tetra-H-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4b) with (S)-(-)-1-phenylethylamine in dry THF. The extraction properties of ligands 5a and 5b towards the some selected α-amino acid methylesters and chiral α-amines are also reported. It has been observed that receptor 5a was an excellent ionophore for α-amino acid methylesters/α-amines and good extractant than 5b. However, both of the ligands did not display any selectivity towards the configurations of this species. in final form: 17 January 2005     

Azocalixarenes. 6: Synthesis, complexation, extraction and thermal behaviour of four new azocalix[4]arenes

Four new azocalix[4]arenes {5,11,17,23-tetrakis[(2-hydroxy-5-tert-butylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (1), 5,11,17,23-tetrakis[(2-hydroxy-5-nitro phenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (2), 5,11,17,23-tetrakis[(2-amino-5-carboxylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (3) and 5,11,17,23-tetrakis[(1-amino-2-hydroxy-4-sulfonicacidnapthylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (4)} have been synthesized from p-tert-butylphenol, p-nitrophenol, p-aminobenzoic acid and 1-amino-2-hydroxy-4-sulphonic acid by diazo coupling reaction with p-aminocalix[4]arene. The resulting ligands (1–4) were treated with three transition metal salts (e.g., CuCl₂·2H₂O, NiCl₂·6H₂O or CoCl₂·6H₂O). Cu(II), Ni(II) and Co(II) complexes of the azocalix[4]arene derivatives were obtained and characterized by UV-vis, IR, ¹H-NMR spectroscopic techniques and elemental analysis. All the complexes have a metal:ligand ratio of 2:1. The Cu(II) and Ni(II) complexes of azocalix[4]arenes are square-planar, while the Co(II) complexes of azocalix[4]arenes are octahedral with water molecules as axial ligands. The solvent extraction of various transition metal cations from the aqueous phase to the organic phase was carried out by using azocalix[4]arenes (1–4). It was found that, azocalix[4]arenes 1, 2 and 3 examined selectivity for transition metal cations such as Ag⁺, Hg⁺ and Hg²⁺. In addition, the thermal stability of metal:azocalix[4]arene complexes were also reported. Dedicated to Prof. Dr. Mustafa Yılmaz on the occasion of his 50th birthday     

Cucurbit[7]uril complexations of bis(isoquinolinium)alkane dications in aqueous solution

The 1:1 and 2:1 host–guest complexation of a series of 1,n-bis(isoquinolinium)alkane dications (Iq(CH₂)_nIq²⁺, n = 2, 4, 5, 6, 8, 9, 10 and 12, and Iq(p-xylene)Iq²⁺) by cucurbit[7]uril (CB[7]) in aqueous solution has been investigated by ¹H NMR spectroscopy and ESI mass spectrometry. The site of binding of the first CB[7] is dependent on the nature of the central linker group, with encapsulation of the p-xylene group or the polymethylene chain when n = 6–10.With shorter (n = 2–5) or longer (n = 12) chains, the first CB[7] binds over an isoquinolinium group. With a second CB[7], the binding of the central group is abandoned in favour of the CB[7] hosts encapsulating the two cationic isoquinolinium termini. The 1:1 and 2:1 host–guest stability constants are related to modes of binding and the nature of the central linkers, and are compared with dicationic guests bearing different terminal groups.     

Pyridazine Derivatives and Related Compounds Part 19: 1 The Synthesis of Different Heterocycles from Ethyl 5-Amino-3,4-diphenylthieno[2, 3-c]pyridazine-6-carboxylate

7-substituted pyrido[2′, 3′: 4, 5]thieno[2, 3-c]pyridazines and 6-substituted pyrimido- [4′, 5′: 4, 5]thieno[2′, 3′: 4, 5]pyridazines were synthesized starting from ethyl 5-aminothieno[2′, 3′: 4, 5]pyridazino-6-carboxylate 1. The reaction of amino ester 1 with benzoyl isothiocyanate affords thiourea derivative 8, which undergoes further transformation to the related fused heterocyclic systems.     

Acid-Catalyzed Regioselective Nitration of o-Xylene to 4-Nitro-o-xylene with Nitrogen Dioxide: Brønsted Acid Versus Lewis Acid

Nitration of o-xylene with nitrogen dioxide imparts remarkable selectivity to 4-nitro-o-xylene. The addition of Brønsted acids and Lewis acids can effectively improve the selectivity for 4-nitro-o-xylene and/or yield, and the Lewis acids present a better influence on the reactions than Brønsted acids do. A 71% yield of mononitro-o-xylene with high selectivity for 4-nitro-o-xylene (ratio 4-/3- = 3.91) has been achieved by the assistance of bismuth trichloride under solvent-free conditions.     

Previously undescribed benzoxepins with bioactivities against inducible pro-inflammatory cyclooxygenase and lipoxygenase from Rhizophora annamalayana Kathir

Two unprecedented benzoxepins were obtained from the ethyl acetate fraction of the leaves of Rhizophora annamalayana Kathir, and characterized as 4-(11-(hydroxymethyl)-10-methylpentan-2-yl)-4, 5-dihydrobenzo[c]oxepin-1(3H)-one (1) and (E)-methyl-14-hydroxy-4-(11-(5-hydroxy-1-oxo-3,4,5-tetrahydrobenzo[c]oxepin-4-yl)ethyl)-10-methylhept-11-enoate (2). The benzoxepin 2 exhibited greater 1, 1-diphenyl-2-picrylhydrazyl and 2, 2′-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid diammonium radical scavenging assays (IC₅₀ 0.68 and 0.84 mg/mL, respectively) than those recorded with 1 (IC₅₀ 0.70 and 0.89 mg/mL, respectively). The tetrahydrobenzo[c]oxepin analogue (2) exhibited significantly great cyclooxygenase-2 and 5-lipoxygenase inhibitory properties (IC₅₀ 0.87 and 0.94 mg/mL, respectively), while compared with its dihydrobenzo[c]oxepin-1(3H)-one isoform (1) (IC₅₀ 1.16 and 1.64 mg/mL, respectively). The dihydrobenzo[c]oxepin-1(3H)-one isoform (2) exhibited significantly greater selectivity index (~2) than synthetic ibuprofen (0.44) (p < 0.05), which attributed the higher anti-inflammatory selectivity of the former against inducible pro-inflammatory cyclooxygenase-2 than its constitutive isoform (cyclooxygenase-1). No significant difference in 5-lipoxygenase (5-LOX) inhibitory activities were apparent between compound 2 (IC₅₀ 0.94 mg/mL) and synthetic ibuprofen (IC₅₀ 0.93 mg/mL).     

Enolethers. XX . Synthesis of azepino[4,5-b]quinoxalines and pyridopyrazino[2,3-d]azepines

1,6-Diethoxy-1,5-hexadiene-3,4-dione ( 1 ) reacts with primary amines 3 and ammonia respectively in a molar ratio of 1:1 to give mainly aminoalkyl- and small amounts of bis(aminoalkyl)-1,5-hexadiene-3,4-diones 4 and 2 , respectively. On heating in dichlorobenzene above 150° the mixtures of 2 and 4 cyclize to yield 1-alkyl-1H-azepine-4,5-diones 5 by elimination of ethanol or amine. 3H-3-Alkylazepino[4,5-b]-quinoxalines 7, 8, 10 and 12 are easily accessible by condensation of the diketones 5a and b with various substituted o-phenylenediamines 6, 9 and 3,3′,4,4′-tetraaminobiphenyl ( 11 ) in p-xylene or n-butanol. 8-Isopropylpyridopyrazino[2,3-d]azepines 14 were obtained by condensation of 5b with pyridinediamines 13 in p-xylene. The azepine-4,5-diones 5a-c can be hydrogenated selectively by sodium borohydride in ethanol at room temperature to give the azepin-4-ol-5-ones 15a-c .     

New approaches to synthesis of tris[1,2,4]triazolo[1,3,5]triazines

Thermal cyclization of 3-R-5-chloro-1,2,4-triazoles (R = Cl, Ph) afforded 2,6,10-tri-R- tris[1,2,4]triazolo[1,5-a:1′,5′c:1″,5″-e][1,3,5]triazines 5 (R = Ph) and 7 (R = Cl). These compounds are first representatives of this class of heterocycles, whose structures were unambiguously established. Treatment of these compounds with nucleophiles (H₂O/NaOH, NH₃) results in the triazine ring opening to give compounds consisting of three 1,2,4-triazole rings linked in a chain. For example, treatment of cyclic compound 5 with aqueous alkali affords 3-phenyl-1-3-phenyl-1-(3-phenyl-1H-1,2,4-triazol-5-yl)-1,2,4-triazol-5-yl-1H-1,2,4-triazol-5-one. Treatment of 3,7,11-triphenyltris[1,2,4]triazolo[4,3-a:4′,3′c:4″,3″-e][1,3,5]triazine (2) with HCl/SbCl₅ leads to the triazine ring opening giving rise to 5-(3-chloro-5-phenyl-1,2,4-triazol-4-yl)-3-phenyl-4-(5-phenyl-1H-1,2,4-triazol-3-yl)-1,2,4-triazole. Thermal cyclization of the latter produces 3,7,10-triphenyltris[1,2,4]triazolo[1,5-a:4′,3′c:4″,3″-e][1,3,5]triazine (13). Thermolysis of both cyclic compound 2 and cyclic compound 13 is accompanied by the Dimroth rearrangement to yield 3,6,10-triphenyl-tris[1,2,4]triazolo[1,5-a:1′, 5′-c:4″,3″-e][1,3,5]triazine (14). Compounds 13 and 14 are the first representatives of cyclic compounds with this skeleton. ¹³C NMR spectroscopy allows the determination of the isomer type in a series of tris[1,2,4]triazolo[1,3,5]triazines.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 706–712, March, 2005.     

Excellent Ag+ selective receptors: Syntheses and complexation properties of novel biscalix[4]arene with benzalazine groups

By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, ¹H NMR and ¹H–¹H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag⁺. The Ag⁺/Na⁺ and Ag⁺/Hg²⁺ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag⁺ was 1.9 × 10⁵ M^? 1 and the 1:1 stoichiometry of receptor 7–Ag⁺ complex was formed. The ¹H NMR spectra complexation experiments suggested that Ag⁺ was bound in a cavity composed of two benzalazine groups on bridging chains.     

Cone di-ionisable calix[4]arene-1,3-crown-5 ligands with elongated pendant side arms: synthesis and metal ion extraction

Abstract

Syntheses of p-H-calix[4]arene-1,3-crown-5 and p-tert-butylcalix[4]arene-1,3-crown-5 ligands with two elongated, proton-ionisable side arms in the cone conformation are described. For solvent extractions from aqueous solution into chloroform, the influence of lengthening the lower rim proton-ionisable side arms and addition of para substituents to the upper rim of the calix[4]crown scaffold on the efficiency and selectivity of metal cation solvent extraction are evaluated.     

1,3-Alternate and C-1,2-Alternate Tetrahomodioxacalix[4]crowns. Crystal Structures and Metal Ion Complexation

Two novel tetrahomodioxacalix[4]crowns with crown-5 and crown-6 rings weresynthesized. From X-ray crystal structures, homooxacalix[4]crown-5 (3) andhomooxacalix[4]crown-6 (2) were found to be in the 1,3-alternate and theC-1,2-alternate conformations, respectively. Homooxacalix[4]crown-5 (1)shows a marked selectivity for cesium ion over other metal ions tested.     

Design and Syntheses of Novel Calix[4]crown: Calix[4]‐Dixanthates‐Crowns

Abstract

A series of novel calix[4]‐dixanthates‐crowns were designed and synthesized by the “1 + 1 condensation” of reacting calix[4]‐1,3‐dixanthate salts derivative (4) with polyethylene glycol ditosylates in 40–60% yields. It was found that the new calixcrowns showed outstanding complexation abilities towards soft cations. Calix[4]‐dixanthate‐crown‐4 (5b) exhibited high complexation selectivity towards Ni²⁺.     

Design and Syntheses of Novel Calix[4](aza)crowns: Neutral Receptors for α‐Amino Acids

A series of novel calix[4](aza)crowns 2a–2d containing acylhydrazone groups was designed and synthesized via 1+1 condensation of calix[4]‐1,3‐substituted benzaldehyde derivative 1 with bis‐hydrazides in 85–90% yields. They showed good complexation abilities toward α‐amino acids and exhibited complexation selectivity toward tryptophane.     

Synthesis of Heteroanellated Pyranosides Starting from Methyl 4,6‐O‐benzylidene‐2,3‐dideoxy‐α‐d‐erythro‐hexopyranosid‐2‐ylidenemalononitrile

The hexopyranosid‐2‐ylidenemalononitrile 1 reacted with phenyl isothiocyanate in the presence of triethylamine to furnish (2R,4aR,6S,10bS)‐8‐amino‐4a,6,10,10b‐tetrahydro‐6‐methoxy‐2‐phenyl‐10‐phenylimino‐4H‐thiopyrano[3′,4′:4,5]pyrano[3,2‐d][1,3]dioxine‐7‐carbonitrile (2). Starting from 1, cyclization with sulphur and diethylamine yielded (2R,4aR,6S,9bR)‐8‐amino‐4,4a,6,9b‐tetrahydro‐6‐methoxy‐2‐phenylthieno[2′,3′:4,5]pyrano[3,2‐d][1,3]dioxine‐7‐carbonitrile (3), which could be transformed into the corresponding aminomethylenamino derivative 4 by treatment with triethyl orthoformate and ammonia. Intramolecular cyclization of 4 to yield (2R,4aR,6S,11bR)‐4,4a,6,11b‐tetrahydro‐6‐methoxy‐2‐phenyl[1,3]dioxino[4″,5″:5′,6′]pyrano[3′,4′:4,5]thieno [2,3‐d]pyrimidin‐7‐amine (5) was achieved by using NaH as base. (2R,4aR,6S,9bS)‐8‐Amino‐4a,6,9,9b‐tetrahydro‐6‐methoxy‐9‐(4‐methylphenyl‐sulfonyl)‐2‐phenyl‐4H‐[1,3]dioxino[4′,5′:5,6]pyrano[4,3‐b]pyrrole‐7‐carbonitrile (6) was prepared by treatment of compound 1 with tosylazide and triethylamine.     

Oxadiazole condensed ring systems,II: Synthesis of new 2-aryl-1,3,4-oxadiazolo[3,2-a]-s-triazine-5,7(6H)-diones

Summary The syntheses of 1,3,4-oxadiazolo[3,2-a]-s-triazine-5,7(6H)-diones4 through the condensation of 2-amino-5-aryl-1,3,4-oxadiazoles1 with ethoxycarbonyl isocyanate2 is described. Methylation of4b with trimethyl phosphate yielded the N-methyl derivative5.

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Kondensierte Ringsysteme des Oxadiazols, 2. Mitt. [1]: Synthese von neuen 2-Aryl-1,3,4-oxadiazolo[3,2-a]-s-triazin-5,7(6H)-dionen

Zusammenfassung Die Synthese von 1,3,4-Oxadiazolo[3,2-a]-s-triazin-5,7(6H)-dionen4 durch Kondensation von 2-Amino-5-aryl-1,3,4-oxadiazolen1 mit Ethoxycarbonylisocyanat2 wird beschrieben. Die Methylierung von4b mit Trimethylphosphat gibt das N-Methyl-Derivat5.

     

The Use of Electrospray Mass Spectrometry (ES/MS) for the Differential Detection of Some Steroids as Calix-[n]-arene Sulphonate Complexes

Non-covalent inclusion complexes formed between three p-sulphonato-calix-[n]-arenes (1 n = 4, 2 n = 6 and 3 n = 8) and three steroids (progesterone, testosterone and oestradiol) have been studied by electrospray mass spectrometry (ES/MS). Mass spectrometric titration experiments have demonstrated differences with regard to selectivity of each p-sulphonato-calix-[n]-arene against the steroids. p-sulphonato-calix-[8]-arene interacts more strongly with oestradiol and p-sulphonato-calix-[6]-arene with progesterone. Studies in which different orifice voltages were applied show that all oestradiol complexes are reduced in signal intensity at 50 V as compared to 20 V, whereas the intensities observed for the testosterone and progesterone complexes do not vary with voltage. Competition experiments confirm the selectivity of the complexation.     

A Convenient Synthesis of Novel Functionalized Pyrimido[5′,4′:4,5]thieno[3,2-c]pyridazines and Related Fused Systems

Possible approaches to the synthesis of functionalized, pyrimido[5′,4′:4,5]thieno [3,2-c]pyridazines 2-18 , pyridazino[3′,4′:4,5]thieno[2,3-d]triazines 19, 20a,b and pyrido[3′,2′:4,5]thieno[3,2-c]pyridazines 22a,b are described. The sequence involves the heterocyclization of 6-amino-1,3-diphenyl-1,4-dihydrothieno[3,2-c]pyridazine-7-carboxamide (1) with appropriate reagents. The antimicrobial activity of some the newly synthesized compounds was examined. All tested compounds proved to be active as antibacterial and antifungal agents.     

芳香桥式双(苯并氮杂-15-冠-5)的合成及其对碱金属和重金属离子的选择键合

通过11,12-苯并-1,7,10,13-四氧杂-4-氮杂环十五烷-11-烯(苯并氮杂-15-冠-5)分别与间二苄溴, 间苯二甲酰氯和对苯二甲酰氯反应, 合成了N,N'-间二苄基双(苯并氮杂-15-冠-5) (1)、N,N'-间苯二甲酰基双(苯并氮杂-15-冠-5) (2)和N, N'-对苯二甲酰基双(苯并氮杂-15-冠-5) (3) 等三个芳香桥式双(苯并氮杂-15-冠-5)衍生物, 并解析了化合物3的晶体结构. 进而采用溶剂萃取的方法研究了它们与一价金属阳离子的键合行为. 结果表明, 双冠醚2对碱金属钠离子和重金属铊离子表现出较高的选择萃取能力, 而双冠醚1对重金属银离子表现出较高的选择萃取能力.