Bifunctional Amine Research Articles

Design of chiral bifunctional secondary amine catalysts for asymmetric enamine catalysis

A series of binaphthyl-based secondary amine catalysts containing various functional groups have been designed as new chiral bifunctional amine catalysts. These chiral organocatalysts have been successfully applied to several asymmetric reactions via enamine intermediates and exhibit unique reactivity and selectivity in comparison with proline and its derivatives.

Chiral Amine Thiourea‐Promoted Enantioselective Domino Michael‐Aldol Reactions Between 2‐Mercaptobenzaldehydes and Maleimides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cross-Linking of C<SUB>60</SUB> Films with 1,8-Diaminooctane and Further Decoration with Silver Nanoparticles

We applied the direct solvent-free functionalization of fullerene C60 with aliphatic bifunctional amine, 1,8-diaminooctane, to prepare chemically cross-linked C60 thin films capable of binding silver nanoparticles. The gas-phase diamine treatment of C60 reduced dramatically the fullerene solubility in toluene, indicating the transformation of pristine C60 into a different solid phase with cross-linked fullerene molecules. Compared to the spectra of pristine C60 film and powder samples, Fourier-transform infrared, UV-Visible, Raman, and 13C nucleic magnetic resonance spectra of the functionalization products exhibited new features, which point to a breaking of C60 ideal structure during the formation of new covalent bonds and to the appearance of sp3 hibridization. The covalent functionalization with 1,8-diaminooctane allowed for a stable and homogeneous deposition of silver nanoparticles of ca. 5-nm diameter onto the functionalized films through the coordination bonding between metal atoms and nitrogen donor atoms of the fullerene derivatives. The proposed mechanism of Ag nanoparticle binding was supported by density functional theory calculations using the hybrid BLYP functional in conjunction with the double numerical basis set DND.

Aglycone geniposidic acid, a naturally occurring crosslinking agent, and its application for the fixation of collagenous tissues

A natural compound, aglycone geniposidic acid (aGSA), originated from the fruits of Gardenia jasminoides ELLIS was used for the fixation of collagenous tissues. The presumed crosslinking reaction mechanism of collagenous tissues with aGSA was inferred by reacting aGSA with a bifunctional amine, 1,6-hexanediamine, using a series of (1)H NMR, FT-IR, and UV/Vis spectra analyses. aGSA reacted with 1,6-hexanediamine by a nucleophilic attack on the olefinic carbon atom at C-2 of deoxyloganin aglycone, followed by opening the dihydropyran ring to form heterocyclic amine compounds. It is inferred that aGSA may form intramolecular and intermolecular crosslinks with a heterocyclic structure within collagen fibers in tissues. The degrees of tissue fixation by aGSA at different pH values were investigated by examining the fixation indices and denaturation temperatures of test samples. It was found that the fixation indices and denaturation temperatures of test samples fixed at neutral or basic pH (pH 7.4 or pH 8.5) were significantly greater than at acidic pH (pH 4.0). The results obtained in this study may be used to elucidate the crosslinking mechanism and optimize the fixation process for developing bioprostheses fixed by aGSA.

Synthesis of 7,8‐Dihydrothieno[3′,2′:4,5]pyrrolo[1,2‐a]pyrazin‐5(6H)‐ones Using a Modification of Four‐Component Ugi Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Organocatalytic enantioselective Michael addition of thioacetic acid to enones

An enantioselective, organocatalytic Michael addition reaction of thioacetic acid with enones has been developed. The process, catalyzed by a chiral bifunctional amine thiourea, furnishes products in excellent yields with up to 63% ee.

Synthesis of 7,8‐Dihydrothieno[3′,2′:4,5]pyrrolo[1,2‐a]pyrazin‐5(6H)‐ones Using a Modification of Four‐Component Ugi Reaction

We describe an efficient synthesis of novel 7,8‐dihydrothieno [3′,2′:4,5]pyrrolo[1,2‐a]pyrazin‐5(6H)‐one heterocyclic structures. The target compounds were prepared by a novel modification of four‐component Ugi reaction of heterocyclic bifunctional keto acids, isonitriles, and amines. We demonstrate the usefulness and versatility of the developed approach, which is amenable to production of combinatorial libraries.

A novel solid-phase synthesis of cyclic guanidines

We have developed a robust solid-phase approach to cyclic guanidines based on the Staudinger protocol. The synthetic sequence involves the reaction of the immobilized aza-Wittig reagents derived from the respective azidobenzoic acids with bifunctional amines. Convenient isolation and good yields of the desired products (34–84%) along with the diversity of the targeted molecules are distinctive features of the resultant library.

Aromatic Diamines as Cooperative Compatibilizers and Impact Modifiers in LDPE/HIPS Blends

Mechanical recycling emerged among other plastics recycling approaches as a profitable method. Its feasibility has enhanced by understanding of reasons of lower mechanical properties of aged materials in comparison with virgin materials, and by a proper exploitation of the knowledge of compatibilization and stabilization additives for upgrading of reused materials. This study deals with low density polyethylene (LDPE). Impact strength of recycled or pre-aged (recyclate model) LDPE / high-impact polystyrene (HIPS) blends compatibilized with styrene-butadiene copolymer / ethylene-propylene elastomer was enhanced and fineness of the phase structure of the system was improved by using N,N'-disubstituted 1,4-phenylenediamine co-additives. Mechanism of the strong synergistic compatibilization effect was explained by LDPE grafting with styrene-butadiene copolymer mediated by the bifunctional amine additive.

Carbodiimide Treatment Dramatically Potentiates the Anticalcific Effect of Alpha-Amino Oleic Acid on Glutaraldehyde-Fixed Aortic Wall Tissue

Background Bifunctional amines were previously found to act as bridging molecules between the terminal ends of incomplete glutaraldehyde (GA) cross-links. The additional cross-links thus formed between ε-NH 2 groups of tissue were seen to significantly inhibit bioprosthetic calcification. In the current study, the potential ability of α-amino oleic acid (AOA) to act as a bridging molecule between ε-NH 2- and COOH-dependent cross-links was hypothesized to similarly augment the anticalcification effect of the AOA molecule. Methods Porcine aortic wall tissue from Medtronic Freestyle valve bioprostheses incorporating the AOA anticalcification process additionally underwent carboxyl-group cross-linking with Jeffamine (poly[propylene glyco]-bis-[aminopropyl ether]) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Tissue was subdermally implanted into 5-week-old Long-Evans rats for 60 days. Standard 0.2% GA-fixed tissue served as a control. To further assess the impact of storage solution on AOA tissue, samples were either stored in GA (0.2%GA) or EDC (25 mmol/L carbodiimide) before implantation. Tissue calcification was assessed by atomic absorption spectroscopy and histochemical staining. Results Aldehyde end-capping with AOA achieved only a modest reduction of calcification in GA-treated aortic wall tissue (−20.0%; p < 0.05). Replacing GA with EDC as a storage solution led to a further 32.4% ( p < 0.01) mitigation of calcification in Freestyle tissue. Incorporating an intermediate EDC/Jeffamine cross-linking step achieved a distinct additional reduction of calcification by 40.4% ( p < 0.05). Overall, aortic wall calcification was 59.7% ( p < 0.0001) lower if commercial Freestyle tissue underwent an additional EDC/Jeffamine cross-linking step and subsequent storage in EDC. Relative to control GA-fixed tissue, this represented a 67.8% ( p < 0.0001) reduction. Incorporation of AOA was essential for the beneficial effect of the additional EDC/Jeffamine cross-linking step. Conclusions Potentially utilizing both the amino- and the carboxyl moieties of AOA for tissue binding dramatically reduces aortic wall calcification of GA-fixed tissue.

Rapid Fluorescent Screening for Bifunctional Amine—Acid Catalysts: Efficient Syntheses of Quaternary Carbon‐Containing Aldols under Organocatalysis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Crystallization kinetics and morphological behavior of reactively processed PBT/epoxy blends

Polybutylene terephthalate (PBT), a versatile engineering thermoplastic, has been processed using epoxy resin as a reactive solvent. Following processing of this blend, the epoxy was cured using a bi-functional amine curing agent, resulting in phase separation and phase inversion thus producing a different morphology. Change in crystallization kinetics of PBT in the presence of the epoxy monomer and cured epoxy resin has been studied using differential scanning calorimetry. Half time of crystallization (t1/2) of PBT decreased in the presence of epoxy monomer while it remained constant in the presence of cured epoxy resin. The value of Avrami exponent varied between 1 and 2 in pure PBT as well as for uncured and cured blends, indicating mixed type of spherulitic growth. Morphology of the uncured and cured blends was studied using small angle light scattering (SALS) and polarizing microscopy for samples crystallized at different temperatures at all levels of the epoxy resin. Scattering pattern in Hv and Vv mode of SALS provided information about the type of spherulites as well as volume filling nature of the spherulites. In general, typical unusual type of spherulitic pattern for PBT, in which scattering lobes lie along the polar axis, changed to usual type of pattern for PBT/epoxy blends, in which scattering lobes lie at 45° to the polar axis.

Some factors influencing the morphology of α-zirconium phosphate and its intercalation reactions with a bifunctional thioether amine

Crystalline samples of α-zirconium phosphate, (α-ZrP, α-Zr(HPO4)2·H2O) have been prepared by decomposition of zirconium fluoride complexes in the presence of phosphoric acid under a variety of conditions. The crystallinity and morphology have been shown to depend on a number of factors including the F−/Zr4+ ratio, the concentration of Zr4+ ions, the material of the reaction vessel and the reaction temperature. Under conditions of rapid precipitation small plate-like crystals of α-ZrP are produced whereas under conditions of slow crystallisation larger crystals with a lower aspect ratio are formed. The relative intensities of the d002, d110 and d112 reflections observed by X-ray powder diffraction show a correlation with the crystal morphology as determined by SEM.

Synthesis of nitrogen heterocycles based on atom transfer carbonylation of bifunctional amines

Abstract Combining atom transfer carbonylations of bifunctional amines with an appropriate choice of cyclization conditions enables the preparation of nitrogen-containing heterocycles via the incorporation of carbon monoxide.

A ‘preformed chelate approach’ model for coupling amine-modified rhenium and technetium ‘3+1’ mixed ligand complexes to carboxylate residues: Crystal structure of ReO[CH 3SCH 2CH 2N(CH 2CH 2S) 2][ p-SC 6H 4NH 2] and ReO[CH 3SCH 2CH 2N(CH 2CH 2S) 2][ p-SC 6H 4NHCOC 6H 5

Selected ‘3+1’ mixed ligand oxorhenium and oxotechnetium complexes containing the SNS/S donor atom set have been modified by introduction of a bifunctional amine anchor on the p-position of the thiophenolato monodentate ligand. A representative series of complexes containing several tridentate ligands was prepared both at macromolar (Re complexes) and nanomolar ( 99mTc complexes) amounts. Coupling of these complexes to activated carboxylate groups was performed according to the ‘preformed chelate approach’ using benzoyl chloride as a model molecule. Coupling yields were high both at nanomolar and millimolar metal concentration, as revealed by high-performance liquid chromatographic analysis of 99mTc and Re species adopting parallel radiometric and photometric detection modes. All Re compounds have been characterized by classical analytical methods. In addition, the structures of representative parent ReO[CH 3SCH 2CH 2N(CH 2CH 2S) 2][ p-SC 6H 4NH 2] and daughter ReO[CH 3SCH 2CH 2N(CH 2CH 2S) 2][ p-SC 6H 4NHCOC 6H 5] complexes were solved by X-ray crystallography. Both compounds adopt a distorted trigonal bipyramidal geometry around rhenium, wherein the oxo group and the sulfur atoms of the SNS ligand occupy the equatorial plane and the nitrogen atom and the sulfur of the monothiol are located at the apical positions trans to each other.

Piperazine as a Linker for Incorporating the Nitric Oxide-Releasing Diazeniumdiolate Group into Other Biomedically Relevant Functional Molecules.

Synthetic procedures have been devised to exploit the bifunctional amine piperazine (pip) as a linker capable of attaching the nitric oxide (NO)-releasing diazeniumdiolate functional group [N(O)NO]- to a diverse selection of biomedically useful molecules. One of the amino groups bears the diazeniumdiolate, which may be substituted on oxygen as necessary to control its dissociation to NO, while the other is used to provide a site suitable for covalent bonding to the molecule requiring NO donor capability. N,N'-Disubstituted piperazines of the structure R-pip-N(O)[Formula: see text]NOE were prepared either by using the nucleophilic character of the amino group or by converting it into an electrophilic moiety for reaction with nucleophilic centers in the molecules to be derivatized. Examples are reported in which E = CH3 and the R groups are bound to the N'-nitrogen: via amide linkages to the carboxyl groups of the drug ibuprofen and the amino acid derivative N-acetylmethionine; through a urea grouping to the ε-amino group of a protected lysine; via a carbamate linkage to poly(ethylene glycol); and by replacing the NH2 nitrogens of nicotinamide and adenosine. Synthesis of analogues in which E = vinyl has been facilitated by introduction of BrCH2CH2OSO2Cl as a novel, efficient bromoethylating agent. Spontaneous NO releasers in the diazeniumdiolated piperazine series include both a fluorescent anion of half-life 5.5 min in which E = Na and R = dansyl and "MOM-PIPERAZI/NO" (E = CH3OCH2, R = H), whose half-life for NO release was estimated as 17 days. The latter agent has made possible the conversion of poly(vinyl chloride) and phosphatidylethanolamine to NO-releasing derivatives. This chemistry should allow introduction of diazeniumdiolate groups into a wide variety of natural products, drugs, polymers, and other molecules whose activities could be beneficially combined with the ability to generate NO for biomedical applications.

ChemInform Abstract: Synthesis of Fused Heterocycles from Chalcones and Bifunctional Amines

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Formation of two stable seven-membered chelate rings bound to one metal center due to addition of bifunctional amine to coordinated nitriles

Reaction of cis- and trans-[PtCl 2(PhCN) 2] with three equivalents of ethylenediamine in water leads to [Pt(NHC(Ph)NHCH 2CH 2NH 2) 2]Cl 2 isolated as bis-hydrate. Metathetical reactions of this complex with NaPF 6 or KSbF 6 in aqueous solution give rise to precipitations of the appropriate [Pt(NHC(Ph)NHCH 2CH 2NH 2) 2]X 2· nH 2O [X = PF 6; n = 3; X = SbF 6; n = 2] salts. The bis-hydrate [Pt(NHC(Ph)NHCH 2CH 2NH 2) 2]Cl 2·2H 2O was also obtained upon treatment of the platinum(IV) complex [PtCl 4(PhCN) 2] with ethylenediamine in the same reaction conditions. The X-ray diffraction analysis performed on a single crystal having formulation [Pt(NHC(Ph)NHCH 2CH 2NH 2) 2](SbF 6) 2 showed that the complex ion contains two unusual seven-membered organic metallacycles bound to the same platinum(II) center.

Polymerizable ring-shaped molecules containing aspartic acid: synthesis and free radical polymerization of a macrocycle derived from (N'-methacryloyl-11-aminoundecanoyl)-α,β-bis(4,9-dioxa-dodecane-1,12-diamine)-L-aspartic acid amide by addition to toluene-2,4-diisocyanate

A novel polymerizable macrocycle, 6, was prepared using high dilution techniques. Starting from N-(N'-methacryloyl-11-aminoundecanoyl)-L-aspartic acid dimethyl ester (2), N-(N'methacryloyl-11-aminoundecanoyl)-α,β-bis( 4,9-dioxadodecane-1,12-diamine)-L-aspartic acid amide (4) was obtained via amino-lysis with the bifunctional amine 4,9-dioxadodecane-1,12-diamine (3) in high excess. Addition of the free amino groups to toluene-2,4-diisocyanate (5) under high dilution provided macrocycle 6. The existence and purity of 6 were confirmed by mass spectrometry, NMR and IR spectroscopy, and HPLC. The methacrylic function was used to build up oligomers by free radical polymerization, using AIBN as an initiator.

Di- bis Pentahydrate von fünf Alkylendiaminen. Eine Fallstudie zu ein- und zweidimensionalen Wasserpolymeren in Festkörpern/Di- to Pentahydrates of Five Alkylenediamines. A Case Study of One- and Two-Dimensional Water Polymers in Solids

The crystal structures of five low-melting hydrates of n-alkane-α,ω-diamines, H2N(CH2)nNH2 · x H2O, for short Cn · x W, have been determined. As a common feature, the water molecules are mutually linked by hydrogen bonds O-H· · ·O to form low-dimensional polymers. These are a meandering chain in C2 · 2 W (space group I 2/a, Z = 4 formula units per unit cell), a zig zag chain in C6 · 2 W (P 21/c, Z = 2), a ribbon of consecutively condensed five-membered rings in C3 · 3 W (P 21/c, Z = 4) and a layer of condensed and spiro-linked rings of varying size each in C7 · 3 W (P 1̄, Z = 4) and C4 · 5 W (C 2/c, Z = 4). Further hydrogen bonding, between the water polymers and the bifunctional amine molecules, leads to overall connectivities which are three-dimensional in each structure.