Ester Amine Research Articles

Chan-Lam Amination of Secondary and Tertiary Benzylic Boronic Esters.

We report a Chan-Lam coupling reaction of benzylic and allylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition-metal-mediated transformation of a tertiary alkylboron reagent. Initial investigation into the reaction mechanism suggests that transmetalation from B to Cu occurs through a single-electron, rather than a two-electron process.

Covalent and Noncovalent Conjugation of Degradable Polymer Nanoparticles to T Lymphocytes.

Cells are attractive as carriers that can help to enhance control over the biodistribution of polymer nanomedicines. One strategy to use cells as carriers is based on the cell surface immobilization of the nanoparticle cargo. While a range of strategies can be used to immobilize nanoparticles on cell surfaces, only limited effort has been made to investigate the effect of these surface modification chemistries on cell viability and functional properties. This study has explored seven different approaches for the immobilization of poly(lactic acid) (PLA) nanoparticles on the surface of two different T lymphocyte cell lines. The cell lines used were human Jurkat T cells and CD4+ TEM cells. The latter cells possess blood-brain barrier (BBB) migratory properties and are attractive for the development of cell-based delivery systems to the central nervous system (CNS). PLA nanoparticles were immobilized either via covalent active ester-amine, azide-alkyne cycloaddition, and thiol-maleimide coupling, or via noncovalent approaches that use lectin-carbohydrate, electrostatic, or biotin-NeutrAvidin interactions. The cell surface immobilization of the nanoparticles was monitored with flow cytometry and confocal microscopy. By tuning the initial nanoparticle/cell ratio, T cells can be decorated with up to ∼185 nanoparticles/cell as determined by confocal microscopy. The functional properties of the nanoparticle-decorated cells were assessed by evaluating their binding to ICAM-1, a key protein involved in the adhesion of CD4+ TEM cells to the BBB endothelium, as well as in a two-chamber model in vitro BBB migration assay. It was found that the migratory behavior of CD4+ TEM cells carrying carboxylic acid-, biotin-, or Wheat germ agglutinin (WGA)-functionalized nanoparticles was not affected by the presence of the nanoparticle payload. In contrast, however, for cells decorated with maleimide-functionalized nanoparticles, a reduction in the number of migratory cells compared to the nonmodified control cells was observed. Investigating and understanding the impact of nanoparticle-cell surface conjugation chemistries on the viability and properties of cells is important to further improve the design of cell-based nanoparticle delivery systems. The results of this study present a first step in this direction and provide first guidelines for the surface modification of T cells, in particular in view of their possible use for drug delivery to the CNS.

Neat synthesis of c-fused pyrroles and its application to macrolactamization

The current study describes an efficient environmental benign synthetic route of N-aryl substituted c-fused pyrrole derivatives via neat approach. It also provides base-mediated intramolecular macrolactamization using amine ester amidation reaction and leads to fused diazocine-6(5H)-one with effective yields.

Formal synthesis of (±)-sedamine through gold(I)-catalyzed intramolecular dehydrative amination of sulfamate esters tethered to allylic alcohols

A concise formal synthesis of (±)-sedamine has been accomplished. The synthesis is straightforward and demonstrates high efficiency. Key steps involve gold(I)-catalyzed cyclization of sulfamate esters tethered to allylic alcohols, sulfamate N-alkylation, and ring-closing metathesis.

Asymmetric copper-catalyzed propargylic amination with amine hydrochloride salts.

The highly enantioselective copper-catalyzed propargylic amination of propargylic esters with amine hydrochloride salts has been realized for the first time using copper salts with chiral N,N,P-ligands. This method features a broad substrate scope and wide functional group tolerance, generating propargylic amines in good to excellent yields with high enantioselectivities (up to 99% ee). The utility of the approach was demonstrated by late-stage functionalization of marketed pharmaceuticals.

Decarboxylative Amination: Diazirines as Single and Double Electrophilic Nitrogen Transfer Reagents.

The ubiquity of nitrogen-containing small molecules in medicine necessitates the continued search for improved methods for C-N bond formation. Electrophilic amination often requires a disparate toolkit of reagents whose selection depends on the specific structure and functionality of the substrate to be aminated. Further, many of these reagents are challenging to handle, engage in undesired side reactions, and function only within a narrow scope. Here we report the use of diazirines as practical reagents for the decarboxylative amination of simple and complex redox-active esters. The diaziridines thus produced are readily diversifiable to amines, hydrazines, and nitrogen-containing heterocycles in one step. The reaction has also been applied in fluorous phase synthesis with a perfluorinated diazirine.

Enantioselective Intermolecular Radical C-H Amination.

Radical reactions hold a number of inherent advantages in organic synthesis that may potentially impact the planning and practice for construction of organic molecules. However, the control of enantioselectivity in radical processes remains one of the longstanding challenges. While significant advances have recently been achieved in intramolecular radical reactions, the governing of asymmetric induction in intermolecular radical reactions still poses challenging issues. We herein report a catalytic approach that is highly effective for controlling enantioselectivity as well as reactivity of the intermolecular radical C-H amination of carboxylic acid esters with organic azides via Co(II)-based metalloradical catalysis (MRC). The key to the success lies in the catalyst development to maximize noncovalent attractive interactions through fine-tuning of the remote substituents of the D2-symmetric chiral amidoporphyrin ligand. This noncovalent interaction strategy presents a solution that may be generally applicable in controlling reactivity and enantioselectivity in intermolecular radical reactions. The Co(II)-catalyzed intermolecular C-H amination, which operates under mild conditions with the C-H substrate as the limiting reagent, exhibits a broad substrate scope with high chemoselectivity, providing effective access to valuable chiral amino acid derivatives with high enantioselectivities. Systematic mechanistic studies shed light into the working details of the underlying stepwise radical pathway for the Co(II)-based C-H amination.

Iron‐Catalyzed Primary C—H Amination of Sulfamate Esters and Its Application in Synthesis of Azetidines†

Summary of main observation and conclusionThe direct amination of unactivated primary C—H bonds is extremely challenging due to their inert nature. Herein, we report an intramolecular primary C—H amination of sulfamate esters using an iron catalyst derived from iron(II) triflate and bipyridine. An array of oxathiazinanes were synthesized in moderate to good yields, which were further converted into biologically important azetidines by a one‐pot procedure. This research demonstrates the potential of applying simple nitrogen ligands in iron‐catalyzed C—H functionalization and offers an accessible alternative to state‐of‐the‐art iron‐nitrene chemistry.

THE POLY(ESTER AMINE)S FUNCTIONAL MAGNETIC CARBON NANOTUBES AS EFFICIENT GENE VECTOR

Magnetic carbon nanotubes have been attracted great interest in biomedicine fields because of their unique structure and magnetic properties. A poly(ester amine)s functional magnetic CNT (CNTs/Fe3O4-HPEI) was prepared and used as gene carrier. The structure was confirmed by FTIR, XRD, TEM, and TGA. The poly(ester amine)s functional magnetic CNTs displayed typical superparamagnetic behavior. Plasmids can be bound by this poly(ester amine)s functional magnetic CNTs to form the nano complexes with positive charge. The gene transfection efficiency is related to the w/w ratio of CNTs/Fe3O4-HPEI and DNA. At the optimal w/w ratio of above 6, the poly(ester amine)s functional magnetic CNTs show a comparable transfection activity to 25k PEI, however the cytotoxicity is much lower. In addition, the gene transfection level can be improved in the magnetic field because of the increased cell internalization rate by magnetic force. These results suggest that the poly(ester amine)s functional magnetic CNTs would be a potential gene vector in targeted gene therapy.

Five new cassane diterpenes from the seeds and bark of Erythrophleum suaveolens

Five new cassane-type diterpenoid heterosides, i. e. two cassane-type amides (1–2), two erythrophlamine-type amine esters (3–4) and a non‑nitrogenous erythrophlamine analogue (5) were isolated from the root barks (1–2) and the seeds (3–5) of Erythrophleum suaveolens. Their structures were unambiguously established by interpretation of their HRESIMS, 1D and 2D NMR data, and chemical degradation for sugar determination. Compounds 3–5 were evaluated for their cytotoxicity against a panel of three cell lines, revealing modest to strong activities.

Synthesis of α-Tertiary Amines by the Ruthenium-catalyzed Regioselective Allylic Amination of Tertiary Allylic Esters

We demonstrated a ruthenium-catalyzed regioselective allylic amination of tertiary allylic esters with various amines using [Cp*Ru(CH3CN)3][PF6]/5,5′-dimethyl-2,2′-bipyridine (5,5′-diMe-2,2′-bpy) a...

Double molecular recognition strategy based on boronic acid-diol and NHS ester-amine for selective electrochemical detection of cerebral dopamine.

Electrochemical detection of dopamine (DA) usually depends on electrochemical oxidation of DA. This conventional method can hardly provide sufficient sensitivity and selectivity in the determination of the cerebral DA down to nanomolar level, because the ability of DA to be electrochemically oxidized is limited and many electroactive interferents are also oxidized at a similar potential with DA. Here, an electrochemical assay based on a double molecular recognition strategy has been proposed and proved to be of high sensitivity and selectivity for DA measurement in the cerebral system. 3,3'-Dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was anchored on the electrode surface to capture DA target through the specific reaction between N-hydroxysuccinimide (NHS) ester and amine. The captured DA endowed the electrode with a layer of diol groups, which further reacted with the boronic acid to trap of 4-mercaptophenylboronic acid (MBA) molecules, thus leading to the conjunction of electroactive thionine (Th) molecules on the electrode for signal readout. In addition, an Au nanostructure was employed to enhance signal amplification and facilitate the double molecular recognition process. As a consequence, this method was able to quantify DA from 1 to 300nM with a detection limit of 0.74nM, which exhibited a high specificity against cerebral interferents. Furthermore, the practicability of this platform was successfully demonstrated through determination of the dynamics of cerebral DA in the events of high K+ and nomifensine retromicrodialysis. Graphical abstract.

Cooperative Catalysis in Amination of β-Hydroxy Carboxylic Acid Esters

Key words cooperative catalysis - ruthenium catalysis - Brønsted acid catalysis - hydroxy esters - benzylamines - amino acid esters

Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters.

The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.

IN VITRO ANTIOXIDANT ACTIVITY AND FOURIER TRANSFORM INFRARED ANALYSIS OF ELAEAGNUS CONFERTA ROXB. LEAF EXTRACT

Objective: The objective of this study was to carry out the antioxidant potential of Elaeagnus conferta (EC) Roxb. leaves that were worked on various assay 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization, total reducing power was studied by ferric reducing antioxidant power (FRAP) and total radical trapping antioxidant potential (TRAP) method. The spectroscopic technique Fourier transform infrared (FTIR) spectrophotometer was performed to detect the characteristic peak values and their functional groups of EC Roxb. 
 Methods: Ethanol solvent is used ABTS, DPPH, FRAP, TRAP, and FTIR analysis.
 Results: ABTS assay, IC50 value was found to be 60 μg/ml compared with standard ascorbic acid 64 μg/ml. DPPH IC50 value of EC Roxb. compared with standard ascorbic acid was found to be 0.43 μg/ml and 0.62 μg/ml. FRAP IC50 value along with standard ascorbic acid was found to be 0.582 μg/ml and 0.596 μg/ml. The IC50 value of TRAP along with standard ascorbic acid was found to be 0.39 μg/ml and 0.62 μg/ml. In FTIR spectroscopic study, it revealed different characteristic peak values with various functional compounds such as phenols, alcohols, amide, alkanes, carboxylic acids, alkenes, primary amines, aromatics, ester, alkyl halides, and aliphatic amines compounds.
 Conclusion: EC Roxb. leaves have a potent rich source of antioxidant. In FTIR analysis, it is confirmed with the presence of phenolic compounds that can be emphasized for efficacy in pharmaceutics.

Amination of \u03b2-hydroxyl acid esters via cooperative catalysis enables access to bio-based \u03b2-amino acid esters

β-amino acid esters are important scaffolds in medicinal chemistry and valuable building blocks for materials synthesis. Surprisingly, the waste-free construction of such moieties from readily available or renewable starting materials has not yet been addressed. Here we report on a robust and versatile method for obtaining β-amino acid esters by direct amination of β-hydroxyl acid esters via the borrowing hydrogen methodology using a cooperative catalytic system that comprises a homogeneous ruthenium catalyst and an appropriate Brønsted acid additive. This method allows for the direct amination of esters of 3-hydroxypropionic acid, a top value-added bio-based platform chemical, opening a simple route to access β-amino acid esters from a range of renewable polyols including sugars and glycerol.

A simple and convenient route to synthesize novel hyperbranched Poly(amine ester) with multicolored fluorescence

Multicolored fluorescence stemed from the nonconventional luminescent polymers without aromatic units is an interesting and meaningful property. So far, a few such polymers bearing multicolored fluorescence are reported; its species, however, are relatively little. Herein, we synthesized a kind of novel water-soluble hyperbranched poly(amine ester) (HPAE) via a straightforward transesterification polycondensation reaction using inexpensive and easily available chemicals. Intriguingly, the pure HPAE could emit blue, green and red luminescence when irradiated by different excitation wavelengths. The TEM result shows that the synergy effect of intra-/intermolecular hydrogen bonds and hydrophobic effect could induce the HPAE to self-assemble and form supramolecular HPAE in water. Such supramolecular HPAE further promote to form stronger through-space conjugation, thus which is favourable for the emission. In addition, the significant solvent and pH dependence profiles of luminescence intensity are also observed. In particular, the HPAE can be used to detect metal ions, and there is strong selective quenching in respect of Fe3+. Therefore, the HPAE show a potential probe for Fe3+.

Amino Acid Organotin Polymers from Diglycine-Synthesis, Structural Characterization and Initial Anticancer Activity

Poly(amine esters) were synthesized from reaction of organotin dichlorides with the dipeptide diglycine. The products were generally high polymers and produced in high yield with yield increasing as the organotin alkyl chain increases in length. Reaction is rapid. Bands characteristic of the formation of the Sn–O–(C=O) and Sn–NH are found in the infrared spectra of the product. MALDI MS and NMR results are consistent with the proposed structure. The products show decent inhibition of all of the tested human solid cancer cell lines including two human pancreatic, two human breast and two human brain cancer cell lines.

Merging photoredox catalysis with transition metal catalysis: Direct C4-H amination of 8-hydroxyquinoline derivatives

A practical and efficient protocol for Ag/Ru-cocatalyzed regioselective C-H amination of 8-hydroxyquinoline esters with pyrazoles was developed, This reaction proceeded smoothly via a photoredox-mediated direct C-H/N-H oxidative coupling process. The remarkable features of this reaction include the wide substrate scope, mild reaction conditions and high regioselectivity at the C4 site of the quinolinyl moiety.

Stereocontrolled concise synthesis of (±)-halosaline through intramolecular C-H amination

Total synthesis of 2-(2-hydroxyalkyl)-piperidine alkaloid (±)-halosaline is described from 7-octen-4-ol using a Rh-catalyzed chemo- and diastereo-selective intramolecular CH amination of sulfamate ester, ring-closing metathesis, and SN2 displacement reaction of the six-membered ring sulfamidate as the key steps.