Use of Stille-type cross-coupling as a route to oligopyridylimines

The new tin reagents, 2-(n-Bu₃Sn)-6-{C(R)OCH₂CH₂O}-C₅H₃N, (R=H a, Me b), have been employed in Stille-type cross-coupling reactions with a range of oligopyridylbromides generating, following a facile deprotection step, a series of formyl- and acetyl-functionalised oligopyridines. Condensation reactions with 2,6-diisopropylaniline has allowed access to families of novel sterically bulky multidentate N,N,N,N (tetradentate), N,N,N,N,N (pentadentate), N,N,N,N,N,N (sexidentate) and N,N,N,N,N,N,N (heptadentate) nitrogen donor ligands. This work represents a straightforward and rapid synthetic route for the preparation of oligopyridylimines, which are expected to act as useful components for the self-assembly of polymetallic complexes.     

New investigation of Vilsmeier-type reaction using pyrazolones with various amides

New investigation of Vilsmeier-type reaction was evaluated to realize the solvent effect by using pyrazolones to react with various of amides, including formamide, N-methylformamide, N-propylformamide, N-tert-butylformamide, N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), N,N-dipropylformamide (DPF), N,N-diisopropylformamide, N,N-dibutylformamide, piperidine-1-carbaldehyde, and pyrrolidine-1-carbaldehyde, in the presence of phosphorous oxychloride POCl₃. The unexpected resulting products were observed in this work according to the difference chemoseletivities of substituted amides. The plausible reactive pathways were proposed to explain the experimental result.     

Antibacterial activity of N-quaternary chitosan derivatives: Synthesis, characterization and structure activity relationship (SAR) investigations

Quaternary N-(2-(N,N,N-tri-alkyl ammoniumyl and 2-pyridiniumyl) acetyl) derivatives of chitosan polymer, chitooligomer, and glucosamine (monomer) were synthesized for the purpose of investigating the structure activity relationship (SAR) for the antibacterial effect. Novel methods were used in the synthesis. The final chitosan and chitooligomer derivatives could thus be obtained in two steps without prior protection of the hydroxyl groups. However, in order to obtain chitosan derivatives with the bulky N,N-dimethyl-N-dodecyl- and N,N-dimethyl-N-butyl side chains three steps were needed, starting from 3,6-O-di-tert-butyldimethylsilyl chitosan (3,6-O-di-TBDMS chitosan) as the key intermediate. The quaternary ammoniumyl acetyl derivatives of glucosamine were synthesized from glucosamine or tetra-O-acetylglucosamine. N,N,N-trimethyl chitosan (TMC) was used as reference compound for investigation of antibacterial activity. Clinical Laboratory Standard Institute (CLSI) protocols were used to determine MIC and MLC for activity against clinically important Gram-positive strains Staphylococcus aureus (ATCC 25923), and S. aureus (MRSA) (ATCC 43300), and Gram-negative strains of Escherichia coli (ATCC 25922), P. aeriginosa (ATCC 27853) and Enterococcus facialis (ATCC 29212). The MIC values for the compounds ranged from 8 to ?8192 mg/L. In general the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitooligomer and glucosamine monomer were more active against bacteria than derivatives with shorter alkyl chains. In contrast the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitosan were less active than derivatives with N-(2-N,N,N-trimetylammoniumyl) acetyl or N-(2-(N-pyridiniumyl) acetyl) quaternary moiety. N,N,N-trimethyl chitosan (TMC) was the most active compound in this study.     

Helicity of N,N′-diaryl-trans-1,2-diaminocyclohexane derivatives. Implications for molecular helicity manipulations

Derivatives of trans-1,2-diaminocyclohexane (DACH), useful as chiral ligands, scaffolds and building blocks, differ in their conformation. The conformation of N,N′-diaryl-DACH derivatives was studied by the semiempirical and DFT computational methods and by exciton-coupled circular dichroism. It was found that, contrary to M-helical N,N′-diimine, N,N′-diimide and N,N′-diamide derivatives, the aromatic residues in N,N′-diphenyl derivatives are oriented to form a P-helix for the (R,R)-DACH absolute configuration. The helicity of the bis-aryl system is modified in the case of 1-naphthyl or 2-naphthyl derivatives. Further switching of helicity has been demonstrated by either protonation or mono-N-acetylation of N,N′-diaryl DACH derivatives.     

Copper(I) catalysis: Synthesis of N,N′-diarylated and N-aryl,N′-formylated chiral C2-symmetric diamines

Chiral N,N′-diaryl C₂-symmetric diamines and N-aryl,N′-formyl-trans-(1R,2R)-diaminocyclohexane are readily accessed by copper catalyzed N,N′-diarylation and N-aryl,N′-formylation of trans-(1R,2R)-diaminocyclohexane with aryl bromides. N,N′-diarylation using (R)-1,1′-binaphthyl-2,2′-diamine and iodobenzene gave the corresponding (R)-N,N′-diphenyl-1,1′-binaphthyl-2,2′-diamine derivative in 83% yield.     

Orthoamides by selective borohydride reduction of N,N′,N″-triacyl- and N,N′,N″-tri(alkoxycarbonyl)-guanidines

N,N′,N″-Triacylguanidines and N,N′,N″-tri(alkoxycarbonyl)guanidines were prepared and reduced with borohydride salts in a mixture of tetrahydrofuran and acetic acid to give triacyl and tri(alkoxycarbonyl) orthoamides in yields of 40–85%. However, similar reduction of N,N′,N″-tri(t-butoxycarbonyl)guanidine did not give orthoamide but the aminal di(t-butyl) methylenedicarbamate.     

Synthesis of 2-methyl-N-(2,2,2-trichloroethylidene)- and 2-methyl-N-(2,2,2-trichloroethyl)benzenesulfonamides from N,N-dichloro-2-methylbenzenesulfonamide and trichloroethylene

The reaction of N,N-dichloro-2-methylbenzenesulfonamide with trichloroethylene gave a new representative of highly electrophilic N-sulfonyl polyhaloaldehyde imines, 2-methyl-N-(2,2,2-trichloroethylidene) benzenesulfonamide. High reactivity of the product was demonstrated in the addition of water and 2-methylbenzenesulfonamide and reactions with benzene, toluene, anisole, thiophene, and 2-chlorothiophene. N,N-Dichlorobenzenesulfonamides and N,N-dichlorotrifluoromethanesulfonamide failed to react with 1,1,3,3,4,4-hexachlorobut-1-ene and 1,1,2,3,4-pentachlorobuta-1,3-diene under the conditions ensuring formation of N-(2,2,2-trichloroethylidene)arenesulfonamides from N,N-dichloroarenesulfonamides and trichloroethylene.     

Dissociation energy of N-H bonds in diatomic aromatic amines

The dissociation energies of N-H bonds (D, kJ/mol) were calculated by the intersecting parabolas method using the kinetic data for the following aromatic diamines: para-phenylenediamine (359.8), N,N′-dimethyl-para-phenylenediamine (348.9), N-dimethyl-N′-methyl-para-phenylenediamine (342.4), N,N′-diphenyl-para-phenylenediamine (352.8), N,N′-diphenylethylenediamine (372.7), N,N′-diheptylethylenediamine (373.3), N,N′-di-(4,4′-ethoxyphenyl)ethylenediamine (363.3), N,N′-di-(4,4′-diisopropylphenyl)-para-phenylenediamine (344.6), 4-{[dimethyl(4-phenylamino)phenoxy)silyl]oxy}-N-phenylaniline (353.4), N,N′-di-β-naphthyl-para-phenylenediamine (354.6), N,N′-di-β-naphthoxy-para-phenylenediamine (353.7), 1,1′-dinaphthyl-2,2′-bis-N,N′-phenyldiamine (372.9), 1,1′-dinaphthyl-2,2′-bis-N,N′-β-naphthyldiamine (384.2), and 2,6-bis[(1E)-1-(2-phenylhydrazin-1-ylidene)ethyl]pyridine (367.9). Individual dissociation energies for the two N-H bonds were determined in N-phenyl-N′-isopropyl-para-phenylenediamine: D(PhN-H) = 352.5 and D(Me₂CHN-H) = 348.7 kJ/mol.     

[4+1] Cycloaddition of N-acylimine derivatives with isocyanides: efficient synthesis of 5-aminooxazoles and 5-aminothiazoles

[4+1] Cycloaddition reaction between isocyanides and N-acylimine derivatives generated from N-acyl N,O-acetals acting as isocyanophiles has been developed. These reactions proceeded smoothly and cleanly to afford the corresponding 5-aminooxazoles in high yields. This reaction was extended to the syntheses of 5-aminothiazoles by using N-thioacyl N,O-acetals. A wide range of N-acyl N,O-acetals, N-thioacyl N,O-acetals, and isocyanides were found to be applicable to this reaction.     

Coupling and cycloaddition of ynamides: homo- and Negishi coupling of tosylynamides and intramolecular [4+2] cycloaddition of N-(o-ethynyl)phenyl ynamides and arylynamides

N,N′-aryl- and N,N′-alkyl-buta-1,3-diyne-1,4-ditosylamides have been synthesized for the first time, in good to excellent yields, by copper-catalyzed dimerization of the corresponding N-aryl or N-alkyl tosylynamides. Negishi coupling of N-ethynylzinc tosylamides derivatives with (hetero)aryl iodides in the presence of Pd₂dba₃ and triphenylphosphine affords N-aryl and N-alkyl arylynamides in yields of up to 90%. Intramolecular [4+2] cycloaddition reactions of N-ethynylphenyl ynamides and arylynamides allow the synthesis of carbazoles and benzannulated and heteroannulated carbazoles in moderate-to-good yields.     

Adsorption of some functionalized aliphatic compounds on plasma-grown thin-film aluminium and magnesium oxides

A study of the inelastic electron tunnelling (IET) spectra of N,N-diethyl-1,2-diaminoethane, N,N′-diethyl-1,2-diaminoethane, N,N′-dimethyl-1,2-diaminoethane, N,N,N′,N′-tetraethyl-1,2-diamino-ethane and N,N,N′,N′-tetramethyl-1,2-diaminoethane, shows all five systems to form five-membered chelate structures with both nitrogen atoms present in the adsorbate acting as Lewis donors at the same cation on either aluminium oxide or magnesium oxide. The IET spectra for the N-ethyl-2-aminoethanol, N,N-diethyl-2-aminoethanol and N,N-dimethyl-2-aminoethanol also examined indicate that similar alkoxy-amino chelated structures are formed with these adsorbates. For the aminoethanols adsorption—chelation appears to involve adsorbate deprotonation and hydroxyl depletion of the oxide surfaces involved with concomitant binding of the nitrogen atom present to the surface metal ion involved in alkoxide formation.     

Recent progress in controlled radical polymerization of N-vinyl monomers

This review summarizes recent advances in the controlled radical polymerization of N-vinyl monomers, such as N-vinylcarbazole, N-vinylindole derivatives, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinylacetoamide derivatives, N-vinyl(na)phthalimides, N-vinylimidazolium salts, and N-vinyltriazoles. Recent significant progress of controlled radical polymerization of these N-vinyl monomers has allowed for the synthesis of well-defined functional polymers having various architectures, including block copolymers, branched polymers (stars, star block copolymers, miktoarm star copolymers, and graft copolymers), and hybrids. Characteristic properties, assembled structures, and three-dimensional architectures of these functional polymers derived from N-vinyl monomers are briefly introduced.     

Étude de la complexation des lanthanides trivalents par les six isomères de l'acide diaminocyclohexane-tétraacétique : Partie 3. Relation entre les Constantes d'Acidité et la Structure Moleculaire des Chélatants

(Study of the complexation of trivalent lanthanides by the six isomers of diaminocyclohexanetetraacetic acid. Part 3. Relationship between the acidity constants and the molecular structure of the ligands.)Potentiometric measurements of the acidity constants of the six isomers of diaminocyclohexane-N,N,N′,N′-tetraacetic acid (DCTA) are reported for an ionic strength of 1 mol l^?1 (KCl) at 25°C. The values of the two constants K_a3 and K_a4 are correlated with the maximum N—N distance for each ligand. Ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) and some homologous ligands, including specially synthesized, 1,8-diaminooctane-N,N,N′,N′-tetraacetic acid and 1,10-diaminodecane-N,N,N′,N′-tetraacetic acid, are studied under the same conditions. It is proved that there is a relationship between the molecular structure and the affinity for protons.     

An efficient,rapid and facile procedure for conversion of aldoximes to nitriles using triphenylphosphine and N-halo sulfonamides

N,N,N＇,N＇-Tetrabromobenzene-1,3-disulfonamide （TBBDA）/triphenylphosphine and N,N,N＇,N＇-tetra- chlorobenzene-1,3-disulfonamide （TCBDA）/triphenylphosphine have been introduced as highly efficient systems for the versatile conversion of aldoxime derivatives into nitriles. The process reported here is operationally simple and reactions have been mildly performed in dichloromethane at room temperature.     

Effect of solvent nature on free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and maleic acid

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in DMSO proceeds to yield statistical copolymers. When the reaction is carried out in methanol, the copolymers of constant compositions (N,N-diallyl-N,N-dimethylammonium chloride: maleic acid = 2: 1) are formed over a wide range of comonomer ratios in the starting mixture. The formation of alternating copolymers in this case may be attributed to formation of donor-acceptor complexes between the comonomers in the methanol solution, as evidenced by UV spectrophotometry. The kinetic features of the process have been investigated, and the relative activities of the monomers have been assessed. ¹³C NMR studies have demonstrated that, regardless of the solvent nature, both double bonds of N,N-diallyl-N,N-dimethylammonium chloride are involved in copolymerization via intermolecular cyclization accompanied by formation of pyrrolidinium structures.     

Synthesis and aromatic nucleophilic N-N, N-S and N-O exchange reactions of N,N-dimethyl-2-trifluoroacetyl-1-naphthylamine

We succeeded in the synthesis of N,N-dimethyl-2-trifluoroacetyl-1-naphthylamine (10) by the regioselective deacylation of N,N-dimethyl-2,4-bis(trifluoroacetyl)-1-naphthylamine with trifluoroacetic acid and water. The aromatic nucleophilic substitutions of 10 with various amines, thiols and alcohols proceeded cleanly to give the corresponding N-N, N-S and N-O exchanged products in moderate to excellent yields.     

Kinetic determination of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid and in a mixture with ethylenediaminetetra-acetic acid

A kinetic method is proposed for the determination of propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid, based on its inhibitory effect on the acetonitrile-catalysed oxidation of Pyrocatechol Violet by hydrogen peroxide. The concentrations of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid determined ranged from 5.0 × 10^?7 to 4.0 × 10^?6 M with a relative standard deviation of up to 3.3%. The same indicator reaction can be applied to the determination of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid and ethylenediaminetetra-acetic acid in mixtures. Mixtures of these acids in molar ratios from 1 ∶ 4.5 to 10 ∶ 1 have been analysed. Concentrations of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid from 2.0 × 10^?7 to 1.0 × 10^?6 M and ethylenediaminetetra-acetic acid from 1.0 × 10^?7 to 9.0 × 10^?7 M were determined with relative standard deviations of up to 4.3 and 5.7%, respectively. The effect of foreign ions on the accuracy of these determinations was also investigated.     

A convenient and efficient method for the synthesis of mono- and N,N-disubstituted thioureas

A convenient method for the synthesis of mono- and N,N-disubstituted thioureas by the debenzoylation of N-substituted- and N,N-disubstituted-N′-benzoylthioureas with hydrazine hydrate under solvent-free conditions has been developed. N-Substituted-N′-benzoylthioureas and hydrazine hydrate were mixed, and stirred at room temperature without a solvent to give the corresponding N-substituted thioureas in high yields.     

Reaction of ferrocenecarboxylic acid with N,N-disubstituted carbodiimides: synthesis, spectroscopic and X-ray crystallographic analysis of N,N-disubstituted N-ferrocenoylureas and identification of a one-pot coupling reagent for the formation of ferrocenecarboxamides in a non-aqueous solvent

N,N^′-dicyclohexyl-N-ferrocenoylurea 2, N,N^′-diisopropyl-N-ferrocenoylurea 3, N,N^′-di-p-tolyl-N-ferrocenoylurea 4 and N,N^′-di-tert-butyl-N-ferrocenoylurea 5 were obtained by reaction of ferrocenecarboxylic acid 1 with N,N^′-dicyclohexylcarbodiimide (DCC), N,N^′-diisopropylcarbodiimide (DIC), N,N^′-di-p-tolylcarbodiimide 10 and N,N^′-di-tert-butylcarbodiimide 11, respectively. Both N-tert-butyl-N^′-ethyl-N-ferrocenoylurea 6 and N^′-tert-butyl-N-ethyl-N-ferrocenoylurea 7 were obtained by reaction of 1 with N-tert-butyl-N^′-ethylcarbodiimide 12. In all cases a small amount of ferrocenecarboxylic anhydride 8 was formed as a by-product. All compounds were characterized by ¹H NMR, ¹³C NMR, IR and MS. Single crystal X-ray structural analyses were made of 2, 3 and 4. From the consistent results, the reaction products of 1 with carbodiimides appear different from those proposed by some earlier workers. With N-(3-dimethylaminopropyl)-N^′-ethylcarbodiimidehydrochloride 9 ferrocenoylurea was not isolated, but the main product was rather 8. The suitability of 8 as acylation reagent was applied by using 9 to obtain N-(3-triethoxysilyl)-propylferrocenecarboxamide in a one-pot reaction from 1 and 3-(triethoxysilyl)-propylamine.     

The influence of N-alkylation and chain length in the coordination ability of diamines towards silver(I) in dimethylsulfoxide

The thermodynamic functions for the complexation of Ag(I) by the following diamines: N,N-dimethyldiethylenediamine (N,N-dmen), N,N-dimethyl-1,3-propanediamine (N,N-dmtn) and N,N,N′,N′-tetramethyl-1,3-propanediamine (tmtn) have been determined in dimethylsulfoxide (dmso) by potentiometric and calorimetric techniques at 298 K and 0.1 mol dm⁻³ ionic strength (NEt₄ClO₄). Only mononuclear complexes are formed (AgL_j ⁺, j=1, 2) where the ligands act as monodentate or chelate agents. All the complexes are enthalpy stabilized whereas the entropy changes counteract the complexation. The different basicities and steric requirements of both the ligands and complexes formed together with the size of the chelate rings are taken into account to discuss the results presented here.