Synthesis and complexing properties of double armed diaza‐15‐crown‐5 and diaza‐18‐crown‐6 ethers having 4′‐hydroxy‐3′,5′‐disubstituted benzyl groups

A series of double armed diaza‐15‐crown‐5 ethers (9a ‐ 16a) and diaza‐18‐crown‐6 ethers (9b ‐ 16b) have been prepared by the Mannich reaction of 2,6‐disubstituted phenols with the corresponding N,N'‐dimethoxymethyldiaza‐crown ethers in benzene. The crystal structures of the diaza‐18‐crown‐6 ethers having iso‐propyl (10b) , tert‐butyl (11b) , and mixed methyl and tert‐butyl groups (12b) at positions 3′ and 5′ of the phenolic side arms were determined using X‐ray diffraction methods. Competitive transport by these ligands for sodium, potassium and cesium cations were measured under basic‐source phase and acidic‐receiving phase conditions.     

Preparation of N‐(4′,6′‐difluoro‐2′‐hydroxybenzyl)‐monoaza‐15‐crown‐5 and x‐ray crystal structure of potassium thiocyanate complex: A molecular partition wall

Armed monoaza‐15‐crown‐5 having a 4′,6′‐difluoro‐2′‐hydroxybenzyl group as an additional binding site ( 2 ) has been prepared by the Mannich reaction of N‐methoxymethylmonoaza‐15‐crown‐5 with 3,5‐difluorophenol. The reactive site on 3,5‐difluorophenol for the Mannich reaction was predicted by an electrostatic potential calculation (density functional calculation, SVWN/DN* method). Ligand 2 is interesting, because it has two possible binding sites (phenolic OH group and fluorine atom) in the side arm. An X‐ray crystal structure of the potassium thiocyanate complex of ligand 2 revealed that the oxygen atom of the phenolic OH group binds to the potassium cation incorporated in the crown ether ring, and two water molecules are enclosed by two armed crown ethers with the crown ethers forming partition walls.     

Double‐Armed Benzo‐15‐crown‐5 Ligands and Complexes and Single Crystal Structure Determination

This work describes the syntheses and characterizations of double‐armed benzo‐15‐crown‐5 containing nitro ( 1 ), amine ( 2 ), and imine ( 3–5 ) groups, and their sodium complexes ( 1a–5a ). Structures of the ligands ( 1–5 ) and sodium complexes ( 1a–5a ) were identified via elemental analyses, and infrared, ¹H‐ nuclear magnetic resonance (NMR), ¹³C‐NMR, and mass spectrometry. The metal extractions were examined by using ultravoilet–visible spectrophotometry. Single crystal for 2 was successfully obtained, and its X‐ray crystal structure was resolved. The compound 2 crystallizes in triclinic, space group p‐1 with a = 9.1420(3), b = 14.9580(4), c = 20.4110(5), and Z = 4.     

Polymer-like structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN complexes with an armed monoaza-15-crown-5 ether bearing a 3',5'-difluoro-4'-hydroxybenzyl group

Structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN complexes with 3',5'-difluoro-4'-hydroxybenzyl-armed monoaza-15-crown-5 ether (5) were investigated. The Li+ and Na+ complexes are (1:1)n polymer-like complexes bridged by hydrogen bonding. On the other hand, the K+, Rb+, and Cs+ complexes are polymer-like complexes bridged by the fluorine atoms of the side arms. The titration calorimetry and 19F NMR titration experiments suggest that one or both fluorine atoms along with the oxygen atom of the phenolic OH group coordinate to the alkali metal ions incorporated in the crown part of a second armed ligand to give polymer-like complexes in solution. The FAB-MS data indicated that larger alkali metal ions form more stable polymer-like complexes.     

Facile synthesis of mono and dibenzo N,N'‐disubstituted diaza 18‐crown‐6 derivatives

This study represents a facile synthesis of building blocks ( 1–3 ) of crown ethers and amine precoursers ( 4a‐d ). The study also involves synthesis of mono and dibenzo N, N‐disubstituted diaza 18‐crown‐6 derivatives with high yield without chromatographic purification and high vacuum distillation. The complex ability of host the ethers was evaluated in terms of structural modification.     

Armed‐azacrown ethers having dual binding sites in a side arm: Complexing abilities and crystal structure of two alkali‐metal complexes

New armed‐monoaza‐12‐crown‐4 and armed‐monoaza‐15‐crown‐5 ethers having dual phenolic OH and pyridine nitrogen binding sites in a side arm were prepared by the Mannich reaction of N‐methoxymethyl‐monoazacrown ethers with 3‐hydroxypyridine. Complexation studies of these new hydroxypyridine‐armed ligands were carried out by liquid membrane transport, ¹H nmr titration experiments, thermodynamic values (log K, ΔH and TΔS), and X‐ray crystallography of two alkali‐metal complexes. These results indicate that the oxygen atom of the phenolic OH group and pyridine nitrogen atom of the side arm are involved in complexation under basic and neutral conditions, respectively.     

Synthesis of (5′S)‐5′‐C‐Alkyl‐2′‐deoxynucleosides

We describe the synthesis of (5′S)‐5′‐C‐butylthymidine ( 5a ), of the (5′S)‐5′‐C‐butyl‐ and the (5′S)‐5′‐C‐isopentyl derivatives 16a and 16b of 2′‐deoxy‐5‐methylcytidine, as well as of the corresponding cyanoethyl phosphoramidites 9a , b and 14a , b , respectively. Starting from thymidin‐5′‐al 1 , the alkyl chain at C(5′) is introduced via Wittig chemistry to selectively yield the (Z)‐olefin derivatives 3a and 3b (Scheme 2). The secondary OH function at C(5′) is then introduced by epoxidation followed by regioselective reduction of the epoxy derivatives 4a and 4b with diisobutylaluminium hydride. In the latter step, a kinetic resolution of the diastereoisomer mixture 4a and 4b occurs, yielding the alkylated nucleoside 2a and 2b , respectively, with (5′S)‐configuration in high diastereoisomer purity (de=94%). The corresponding 2′‐deoxy‐5‐methylcytidine derivatives are obtained from the protected 5′‐alkylated thymidine derivatives 7a and 7b via known base interconversion processes in excellent yields (Scheme 3). Application of the same strategy to the purine nucleoside 2′‐deoxyadenine to obtain 5′‐C‐butyl‐2′‐deoxyadenosine 25 proved to be difficult due to the sensitivity of the purine base to hydride‐based reducing agents (Scheme 4).     

Complexation of Alkali Triflates by Crown Ethers: Synthesis and Crystal Structure of [Na(12‐crown‐4)2][SO3CF3], [Na(15‐crown‐5)][SO3CF3], [Rb(18‐crown‐6)][SO3CF3], and [Cs(18‐crown‐6)][SO3CF3]

Complexes of trifluoromethanesulfonates (triflates) with alkali metals Na, Rb, Cs have been prepared in the presence of various macrocyclic polyether crowns [(12‐crown‐4), (15‐crown‐5) and (18‐crown‐6)]. Depending on the combination of alkali ion with crown, the complexes include separated ion pairs [Na(12‐crown‐4)₂] [SO₃CF₃] ( 1 ) and contact ion pairs [Na(15‐crown‐5)] [SO₃CF₃] ( 2 ), [Rb(18‐crown‐6)] [SO₃CF₃] ( 3 ), and [Cs(18‐crown‐6)] [SO₃CF₃] ( 4 ), in which the triflate acts as a bidentate ligand. It is shown that the choice of crown ether is of paramount importance in determining the solid‐state structural outcome. The complex resulting from the pairing of crown ether ( 1 ) develops, when the crown ether is too small in relation to the alkali ion radius. When the cavity size of the crown ether is matched with the alkali ion radius, simple monomeric structures are identified in 2 , 3 and 4 . The title compounds crystallize in the monoclinic crystal system: 1 : space group P2/c with a = 9.942(3), b = 11.014(2), c = 10.801(3) Å, β = 97.30(2)°, V = 1173.1(4) ų, Z = 2, R1 = 0.0812, wR2 = 0.1133: 2 : space group P2₁/m with a = 7.949(2), b = 12.063(3), c = 9.094(2) Å, β = 105.98(2)°, V = 838.3(4) ų, Z = 2, R1 = 0.0869, wR2 = 0.1035: 3 : space group P2₁/c with a = 12.847(5), b = 8.448(2), c = 22.272(6) Å, β = 122.90(3)°, V = 2029.5(1) ų, Z = 4, R1 = 0.0684, wR2 = 0.1044: 4 : space group P2₁/n with a = 12.871(3), b = 8.359(1), c = 19.019(4) Å, β = 92.61(2)°, V = 2044.2(6) ų, Z = 4, R1 = 0.0621, wR2 = 0.0979.     

Density functional theory study of a molecular allosteric switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5

A classical model of “molecular machine,” which acts as an ON–OFF switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5 ( L ), has been theoretically studied. It is highly important to understand the mechanism of this switch. The alkali‐metal cations (Na⁺ and K⁺) and W(CO)₄ fragment are introduced to coordinate with the different active sites of L , respectively. The density functional theory (DFT) method is used for understanding the stereochemical structural natures and thermodynamic properties of all the target molecules at B3LYP/6‐31G(d) and SDD (Stuttgart–Dresden) level, together with the corresponding effective core potential (ECP) for tungsten (W). The fully optimized geometries have been performed with real frequencies, which indicate the minima states. The nucleophilicity of L has been investigated by the Fukui functions. The natural bond orbital analysis is used to study the intermolecular charge‐transfer interactions and explore the origin of the internal forces of the molecular switch. In addition, the binding energies, enthalpies, Gibbs free energies, and the cation exchange energies have been studied for L , W(CO)₄ L , and their corresponding complexes. The properties of the complexes displayed by in presence or absence of the W(CO)₄ fragment are also analyzed. The calculated results of allosterism displayed by L are in a good agreement with the experimental results. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011     

Strukturen der Alkalimetallsalze aromatischer,heterocyclischer Amide: Synthese und Struktur von Kronenether‐Addukten der Alkalimetall‐indolide

Structures of Alkali Metal Salts of Aromatic, Heterocyclic Amides: Synthesis and Structure of Crown Ether Adducts of the Alkali Metal Indolides The synthesis of five alkali metal indolide crown ether complexes is reported. Lithium‐indolide(12‐crown‐4) ( 1 ) was synthezised from butyllithium, indole, and 12‐crown‐4; sodium‐indolide(15‐crown‐5) ( 2 ) from sodium metal, indole, and 15‐crown‐5; potassium‐indolide(18‐crown‐6) ( 3 ) from potassium hydride, indole, and 18‐crown‐6. Rubidium‐ and cesium‐indolide(18‐crown‐6) ( 4 , 5 ) were made from Rb‐ and Cs‐hexamethyldisilazide, indole, and 18‐crown‐6. The structures of 2 , 4 , and 5 could be determined by X‐ray diffraction. The complexes 2 and 4 are mononuclear, the indolide anion shows an η¹(N)‐coordination to the metal cation. Complex 5 is dinuclear with a central [Cs—N—]₂‐ring.     

Synthesis,properties and solid state structure of 5‐diphenylphosphino‐2‐hydroxy‐1,3‐xylyl‐18‐crown‐5

5‐Diphenylphosphino‐2‐hydroxy‐1,3‐xylyl‐18‐crown‐5 has been synthesized from 5‐bromo‐2‐hydroxy‐18‐crown‐5 by reacting it in sequence at low temperature with n‐butyl lithium and methyl diphenylphosphonite. The phosphorous donor properties of this phenol phosphine (OH derivative) and the corresponding phenoxide (O^? derivative) have been studied in the presence and absence of alkali metal ions by determining the frequencies of the A₁ ν(CO) bands of Ni(CO)₃L complexes. For the OH and O^? derivatives, the latter generated by addition of CsOH to the former, the ν(CO) bands are observed at 2067.6 and 2063.4 cm^?1, respectively, providing the trend predicted by Hammett parameters for OH and O^? substituents. Addition of Na⁺ or K⁺ to the OH derivative has little effect on this stretching frequency, but the former ion shifts the O^? derivative band to 2067.7 cm^?1 A solid state structure has been obtained of the OH derivative, and two independent molecules were found in the unit cell. Both have a single water molecule hydrogen bonded to two across‐ring oxygen atoms and the phenol hydrogen. The crown ether ring has the usual gauche and anti arrangements for the C‐C and C? O bonds.     

Synthesis of 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4′′‐hydroxyphenyl)‐thiazoles and their O‐glucosides

In continuation of our work, we synthesized 2‐(sulfamoylphenyl)‐4′‐amino‐4‐(4″‐hydroxyphenyl)‐thiazole ( 3a ), which were reacted with various (aryl/hetroaryl) aldehyde to form 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐hydroxyphenyl)‐thiazoles ( 4a , 4b , 4c , 4d , 4e , 4f ). Glucosylation of compounds ( 4a , 4b , 4c , 4d , 4e , 4f ) have been done by using acetobromoglucose as a glucosyl donor to afford 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(2,3,4,6‐tetra‐O‐acetyl‐4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 5a , 5b , 5c , 5d , 5e , 5f ), further on deacetylation to produce 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 6a , 6b , 6c , 6d , 6e , 6f ). The compounds are confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR, and ES‐Mass spectral analysis. J. Heterocyclic Chem., (2011).     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

Synthesis,properties and X‐ray structure of 5‐azido‐2‐methoxy‐1,3‐xylyl‐18‐crown‐5

5‐Azido‐2‐methoxy‐1,3‐xylyl‐18‐crown‐5 has been prepared by reacting p‐toluenesulfonyl azide with the carbanion generated from the reaction of 5‐bromo‐2‐methoxy‐1,3‐xylyl‐18‐crown‐5 with n‐butyl lithium. The asymmetric N₃ stretch of this product has been observed as a single band at 2110 cm^?1 in dichloromethane solution. Addition of solid NaSCN, KSCN and CsSCN shifts this band to 2115, 2113 and 2112 cm^?1, respectively. Computational studies of this azide at the B3LYP‐6‐31G* level in the presence and absence of Na⁺ predicted these bands to be at 2173 cm^?1 and 2184 cm^?1. For the salt‐containing solutions, additional bands were observed at 2066 cm^?1, 2056 cm^?1 and 2055 cm^?1, respectively, which are in the range expected for CN stretches. The X‐ray structure of this azide has been determined. The terminal and internal N? N bond lengths were found to be 1.127(2) and 1.245(2) Δ, respectively, which is the usual pattern for aromatic azides. The crown ether is looped over the face of the aromatic ring resulting in an angle of 38.94° between the plane defined by the aromatic ring and that defined by the five ring oxygen atoms. In addition, the CH₃ group is rotated out of the plane of the phenyl ring with C1‐C18‐O181‐C182 and C17‐C18‐O181‐C182 dihedral angles of 93.81(14)° and ‐90.54(14)°, respectively.     

Crown Ether Phase Transfer Catalysts for An Ionic Polymerization of Bisphenol A / 4,4′‐Dichlorodiphenyl Sulfone

Various crown ethers were prepared and applied as phase transfer catalysts for the an ionic copolymerization of bisphenol A and 4,4′‐dichlorodiphenyl sulfone monomers with alkali salts, e.g., NaNH₂, NaOH and KOH, as initiators. The catalytic abilities of various crown ethers for the an ionic polymerization of bisphenol A / 4,4′‐dichlorodiphenyl sulfone were found to be in the order: 15‐crown‐5 ? monobenzo‐15‐crown‐5 > 18‐crown‐6 > Dicyclohexano‐18‐crown‐6 > Dibenzo‐18‐crown‐6 > 12‐crown‐4 with sodium amide (NaNH₂) as initiator. Sodium amide was shown to be a better initiator than NaOH or KOH with monobenzo‐ 15‐crown‐5 as a catalyst. Effects of solvents and temperature on the crown ether catalytic polymerization were also investigated. Dimethyl sulfoxide (DMSO) exhibited much better for the polymerization than other organic solvents, e.g., toluene, p‐xylene, dimethyl formamide and dioxane. Higher polymerization was found at higher temperatures and about 100% yield of poly(bisphenol A / sulfone) was obtained at 125 °C in 3 hr. The molecular weight of poly(bisphenol A / sulfone) as a function of reaction time was determined with gel permeation chromatography. Concentration effects of crown ether on % yield and molecular weight of poly(bisphenol A / sulfone) were also investigated and discussed.     

Invariom‐model refinement and Hirshfeld surface analysis of well‐ordered solvent‐free dibenzo‐21‐crown‐7

Crown ethers and their supramolecular derivatives are well‐known chelators and scavengers for a variety of cations, most notably heavier alkali and alkaline‐earth ions. Although they are widely used in synthetic chemistry, available crystal structures of uncoordinated and solvent‐free crown ethers regularly suffer from disorder. In this study, we present the X‐ray crystal structure analysis of well‐ordered solvent‐free crystals of dibenzo‐21‐crown‐7 (systematic name: dibenzo[b ,k ]‐1,4,7,10,13,16,19‐heptaoxacycloheneicosa‐2,11‐diene, C₂₂H₂₈O₇). Because of the quality of the crystal and diffraction data, we have chosen invarioms, in addition to standard independent spherical atoms, for modelling and briefly discuss the different refinement results. The electrostatic potential, which is directly deducible from the invariom model, and the Hirshfeld surface are analysed and complemented with interaction‐energy computations to characterize intermolecular contacts. The boat‐like molecules stack along the a axis and are arranged as dimers of chains, which assemble as rows to form a three‐dimensional structure. Dispersive C—H…H—C and C—H…π interactions dominate, but nonclassical hydrogen bonds are present and reflect the overall rather weak electrostatic influence. A fingerprint plot of the Hirshfeld surface summarizes and visualizes the intermolecular interactions. The insight gained into the crystal structure of dibenzo‐21‐crown‐7 not only demonstrates the power of invariom refinement, Hirshfeld surface analysis and interaction‐energy computation, but also hints at favourable conditions for crystallizing solvent‐free crown ethers.     

Synthesis of dibenzo‐16‐crown‐5 compounds with pendant ester and ether groups

Structurally related dibenzo‐16‐crown‐5 lariat ethers with pendant ester and ether groups are prepared. Structural variations within the series of alkyl lariat ether esters include changes in the O‐alkyl group, attachment site and nature of the lipophilic group, and length of the spacer, which connects the ester group to the polyether framework. Also synthesized are bis(crown ether) diesters with two dibenzo‐16‐crown‐5 or two dicyclohexano‐16‐crown‐5 units and two ester groups connected to each other by a linker of varying length. Synthetic strategies for the preparation of these lariat ethers with pendant ester‐ and ether‐containing side arms are described.     

Investigation of Some Functionalization Reactions of 4‐Benzoyl‐5‐phenyl‐1‐(4‐methoxyphenyl)‐1H‐pyrazole‐3‐carbonyl Chloride and Their Antimicrobial Activity

The 1H‐pyrazole‐3‐carboxylic acid 1 was converted via reactions of its acid chloride 3 with various asymmetrical disubstituted urea and alcohol derivatives into the corresponding novel 4‐benzoyl‐N‐(N′,N′‐dialkylcarbamyl)‐1‐(4‐methoxyphenyl)‐5‐phenyl‐1H‐pyrazole‐3‐carboxamide 4a , b and alkyl 4‐benzoyl‐1‐(4‐methoxyphenyl)‐5‐phenyl‐1H‐pyrazole‐3‐carboxylate 7a‐c , respectively, in good yields (57%‐78%). Friedel‐Crafts reactions of 3 with aromatic compouns for 15 min.‐2 h led to the formation of the 4‐3‐diaroyl‐1‐(4‐hydroxyphenyl)‐5‐phenyl‐1H‐pyrazoles 9a‐c , 4‐benzoyl‐1‐(4‐methoxyphenyl)‐3‐aroyl‐5‐phenyl‐1H‐pyrazoles 10a , b and than from the acylation reactions of 9a‐c were obtained the 3,4‐diaroyl‐1‐(4‐acyloxyphenyl)‐5‐phenyl‐1H‐pyrazoles 13a‐d . The structures of all new synthesized compounds were established by NMR experiments such as ¹H, and ¹³C, as well as 2D COSY and IR spectroscopic data, and elemental analyses. All the compounds were evaluated for their antimicrobial activities (agar diffusion method) against eight bacteria and two yeasts.     

Synthesis of N—（4—Salicylideneiminoaryl）monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt（Ⅱ）Complexes

The Schiff base‐containing pendant monoaza crown ether HL¹, HL², HL³ and HL⁴ have been synthesized by condensation of salicylaldehyde with N‐(4‐aminoaryl) monoaza crown ethers, which were prepared conveniently from 4‐nitro‐N, N‐di(hydroxyethyl) aniline or 4‐nitrobenzyl chloride via cyclization or condensation and reduction. The structures of HL¹—HL⁴ were verified by ¹H NMR, IR spectra, MS and elemental analysis. Moreover, the oxygenation constants (KO2) and thermodynamic parameters (δH⁰ and δS⁰) of their cobalt(II) complexes were determined in the range of ?5 °C to 25 °C, and the effect of crown ring bonded to a Schiff base on the dioxygen affinities of cobalt(II) complexes was also observed as compared to the uncrowned analogue (CoL).     

Syntheses,structure, and electrochemical properties of unsymmetrical crown‐annelated TTF derivatives

A series of new crown‐ether annelated TTF derivatives 2a, 2b, 2c, 3 and 5 have been synthesized and characterized by melting points, NMR, IR and ESI‐MS. The crystal structure of compound 3 , 2, 3‐dithia‐(5′,8′‐dioxaoctyl)‐6,7‐ethylenedithiatetrathiafulvalene, has been determined by X‐ray crystallography. Redox properties of all these compounds have been investigated by cyclic voltammetry and each compound shows two reversible single‐electron redox couples. The results indicate that 3 is responsive for Li⁺, but not to other alkali metal cations, such as Na⁺ and K⁺. Although with the same cavity, compounds 2c and 5 show marked changes upon the addition of sodium perchlorate, while there is no significant response for 2a and 2b at the same condition.