Amino Ether Research Articles

Functionalized α‐Fluorinated Amines from Imines and Enol Ethers

AbstractWe report the addition reaction of lithium enol ethers to fluoroalkyl imines. A range of different fluoroalkyls and lithiated reagents are well tolerated. Diastereoselective addition of lithium vinyl ethers to fluoroalkyl N‐tert‐butylsulfinylimines is disclosed, providing enantiomerically enriched α‐fluorinated amines in up to 98% yield. This general approach led to the diastereoselective formation of various amino alcohols and amino ethers, which are difficult to obtain by other methods.

Asymmetric Total Synthesis of (+)-Chuanxiongnolide L1 via a Stereoselective Oxidative Dearomatization/Diels-Alder Strategy.

The first asymmetric total synthesis of chuanxiongnolide L1 was achieved in 16 steps and 1.9% overall yield by employing a bioinspired chiral auxiliary strategy. The key steps involving asymmetric oxidative dearomatization of chiral amino ether and subsequent asymmetric Diels-Alder reaction of the resulting masked chiral ortho-benzoquinone were adopted.

Synthesis of Chiral Vicinal Amino Alcohol Derivatives via Lewis Acid‐Catalyzed Asymmetric Ring Opening of Aziridines with Alcohols and Carboxylic Acids

AbstractUnder the catalysis of a Cu(I) or Ag(I) salt with a chiral diphosphine ligand, the enantioselective nucleophilic ring opening of racemic 2‐styrenylaziridines via kinetic resolution or dynamic kinetic asymmetric transformation (DyKAT) and of meso aziridines via desymmetrization with alcohols was realized. The reaction provided a range of chiral vicinal amino ether derivatives in 47%‐98% yields and with 50%–98% ee. The reaction could be extended to aliphatic carboxylic acids as nucleophiles. The synthetic utility was demonstrated in a four‐step formal synthesis of a diastereomer of the antirythmetic agent vernakalant.

Catalytic Aminium Radical-Cation Salt (Magic Blue)-Initiated SN2-Type Nucleophilic Ring-Opening Transformations of Aziridines.

A simple and atom economic protocol for the construction of C-X/C-C bonds via catalytic aminium radical-cation salt (Magic Blue)-initiated SN2-type nucleophilic ring-opening transformations of racemic and nonracemic aziridines with different hetero and carbon nucleophiles to afford various amino ethers, thioethers, and amines in up to 99% yield, and with perfect enantiospecificity for some substrates but reduced ee with others (for nonracemic aziridines), is developed. This aminium radical-cation salt-initiated, SN2-type nucleophilic ring-opening strategy, along with various cyclization protocols, is employed to synthesize various biologically significant compounds.

Enantioselective aminomethylation of 1-(benzyloxy)propan-2-one with an aromatic C-ethyl substituted propargyl amine ether

Enantioselective aminomethylation of 1-(benzyloxy)propan-2-one with an aromatic propargyl amino ether in the presence of a chiral pseudoephedrine catalyst in an aqueous medium gave anti / syn products with high yields and optical purity.

Ring-Opening Cyclization (ROC) of Aziridines with Propargyl Alcohols: Synthesis of 3,4-Dihydro-2H-1,4-oxazines.

Activated aziridines react with propargyl alcohols in the presence of Zn(OTf)2 as the Lewis acid catalyst following an SN2-type ring-opening mechanism to furnish the corresponding amino ether derivatives. Those amino ethers further undergo intramolecular hydroamination via 6-exo-dig cyclization in the presence of Zn(OTf)2 as the catalyst and tetrabutylammonium triflate salt as an additive under one-pot two-step reaction conditions. However, for nonracemic examples, ring-opening and cyclization steps were conducted under two-pot conditions. The reaction works well without any additional solvents. The final 3,4-dihydro-2H-1,4-oxazine products were obtained with 13 to 84% yield and 78 to 98% enantiomeric excess (for nonracemic examples).

Molecular Simulation of Pervaporation on Polyurethane Membranes.

This article discusses a molecular simulation of membrane processes for the separation of liquid mixtures during pervaporation. A method for simulating the structure of polyurethane membranes was developed. The method was based on the known mechanisms of the formation of macromolecules from constituent monomers. For the formation of a chemical bond between the monomers, values of the parameters of the potentials of intermolecular interactions were set so that bonds were formed only between the corresponding atoms. The algorithm was validated to produce polymer films from diphenylmethane diisocyanate (MDI) and amino ethers of boric acid (AEBA). The polymer film obtained according to the developed algorithm was used to study the adsorption of ethanol and water. The concentration distributions of the components inside the polymer film were obtained for films of various thicknesses. Modifications of the DCV-GCMD method were proposed for the molecular simulation of pervaporation. The algorithm was based on maintaining a constant density of the mixture in the control volume. After the molecules were added to the control volume, thermodynamic equilibrium was established. During this process, molecules moved only in the control volume, while the rest of the molecules were fixed. The proposed algorithm was used to calculate the flows of water and ethanol through the polymer film.

Visible light-mediated three-component functionalization of olefins with sulfoxyimidoylsulfonium salt for the synthesis of β-amino alcohols and amino ethers.

A new strategy involving three-component functionalization of olefins with sulfoxyimidoylsulfonium salt and a nucleophilic reagent for the synthesis of β-amino alcohols and β-amino ethers by photoredox catalysis was developed. The sulfoxyimidoylsulfonium salt is important and serves as the N-centred radical precursor. β-Amino alcohols and β-amino ethers bearing various functional groups are synthesized in good yields under mild conditions. Furthermore, the advantages of this strategy are greater safety, no additives, and easy to obtain raw materials.

Hydroxyl–yne click polymerization: a facile strategy toward poly(vinyl amino ether ester)s with color-tunable luminescence

This study established an environmentally friendly hydroxyl–yne click polymerization, which provides a new strategy for the preparation of color-tunable unconventional luminescent materials.

Amphiphilic Polyfluorinated Amino Ethers from Cyclic Sulfamidates.

Regioselective ring opening of cyclic sulfamidates was achieved by means of nucleophilic polyfluorinated alkoxides to access achiral and chiral β- and γ-ORF amines and α-amino esters. Subsequent transformations provide free amines ready for incorporation into bioactive substances through amide bond formation or nucleophilic aromatic substitution.

PH‐responsive amine‐based fluorescent polymers with on–off switchable and concentration‐dependent fluorescence behaviors

AbstractIn this paper, pH‐responsive fluorescent poly(amino ether ester)s with reversible “on–off” switching fluorescence and concentration‐dependent emission behavior were reported. A remarkable difference fluorescence behavior was observed at diverse polymer concentrations with pH values. Moreover, at all investigated concentrations, poly(amino ether ester)s can respond to acid pH and exhibit extreme acid‐induced fluorescence quenching phenomenon. Dynamic light scattering and transmission electron microscopy analyses confirmed that the fluorescence quenching phenomenon is due to the aggregation, which was caused by the protonation of tertiary amine groups in poly(amino ether ester)s under extreme acidic conditions. Interestingly, the quenched fluorescence can be completely recovered by adding an alkaline solution, thereby enabling an “on–off” switch function by adjusting the pH value. Most importantly, the pH‐responsive fluorescent poly(amino ether ester)s exhibit good biocompatibility and cellular imaging, and its cellular imaging function is highly sensitive to acid pH. Thus, this study opens a new idea for the preparation of amine‐based fluorescent polymers as stimuli‐responsive fluorescent probe for cellular imaging, drug delivery, and disease diagnostics.

Amino ether analogues of 4,4′-dihydroxy-3-methoxy-6,7′-cyclolignan and their activity against drug-resistant bacteria

Larrea tridentata antibacterial lignan 4,4′-dihydroxy-3-methoxy-6,7′-cyclolignan ( 1 ) was derivatized to obtain eleven new amino ether derivatives ( 2 A - 12 C ). The structural elucidation of compounds was performed by analysis of 1D- and 2D NMR spectral data and HRESIMS. The antibacterial activity of compounds was determined against nine drug-resistant bacteria and two strains of Mycobacterium tuberculosis (sensitive ATCC 27294 H37Rv and drug-resistant G122). Results showed that all derivatives were devoid of activity towards six gram-negative clinical isolates assayed. However, seven derivatives displayed antibacterial activity against three gram-positive drug-resistant bacteria. Further, enhancement of antibacterial activity was only observed for the compounds 2 A and 10 C - 12 C (MIC of 12.5 µg/mL) which were two-fold more active than the starting material 1 against vancomycin-resistant Enterococcus faecium . All derivatives, except compound 9 B , showed antitubercular activity against both M. tuberculosis strains. Interestingly, all the compounds, except for 2 A and 11 A , were more active than the starting material 1 (MIC of 50 µg/mL). Compound 4 C was the only compound as active as the positive control ethambutol against the drug-resistant strain M. tuberculosis G122 (MIC of 6.25 µg/mL). In addition, the derivative 7 C was the most active compound against the sensitive strain M. tuberculosis H37Rv (MIC of 6.25 µg/mL) • Aminoether analogues of 4,4′-dihydroxy-3-methoxy-6,7′-cyclolignan were synthesized. • The antibacterial activity of the compounds was determined. • 4 C was as active as the control drug ethambutol against a multidrug resistant Mtb strain.

Amino Ethers of Ortho-Phosphoric Acid as Extragents for Ethanol Dehydration

Amino ethers of ortho-phosphoric acid prepared using triethanolamine; ortho-phosphoric acid; polyoxyethylene glycol, diethylene glycol, triethylene glycol and glycerol (AEPA-DEG/TEG/Gl) were investigated as extractants for the separation of aqueous ethanol solutions by extractive distillation. Using the method of open evaporation, the influence of the molecular structure of AEPA-DEG/TEG/Gl on the conditions of vapor–liquid equilibrium in ethanol–water solutions was studied. It has been shown that the addition of AEPA-DEG/TEG/Gl removes the azeotropic point. At the same time, the observed effect turned out to be significantly higher in comparison with the use of pure glycerol or glycols for these purposes. The UNIFAC model was used to calculate the activity coefficients in a three-component ethanol–water–AEPA-DEG/TEG/Gl mixture. Within the framework of this model, a division of AEPA-DEG/TEG/Gl molecules into group components is proposed. Previously unknown parameters of the groups PO–CH, PO–CH2, PO–OCH2, PO–NHCH2, PO–OH, and PO–H2O were determined from our own and published experimental data. The concentration dependences of the density and dynamic viscosity of AEPA-Gl aqueous solutions have been experimentally measured. Experimental studies of the extractive distillation of ethanol–water using AEPA-Gl as an extractant have been carried out in a column with bubble cap plates and a packing, and its high efficiency has been established.

Thermal Behavior of Polyurethane Ionomers Based on Amino Ethers of Orthophosphoric Acid

The products of triethanolamine- and triethylamine-catalyzed reactions of etherification of orthophosphoric acid using poly(oxypropylene glycol)-1000 are studied. It is shown that the nature of tertiary amine markedly influences the completeness of the etherification reaction. When using triethanolamine, its hydroxyl groups are also involved in the etherification of orthophosphoric acid. The resultant tertiary ammonium, which is a central unit of the synthesized branched amino ethers of orthophosphoric acid, is responsible for incomplete etherification and existence of space-separated ionic pairs in the structure of amino ethers. In the case of triethylamine, the etherification of orthophosphoric acid occurs almost completely to yield polyphosphates. The thermal behavior of ionomeric and nonionomeric polyurethanes is investigated. It is found that, for polyurethanes containing ionic groups, the glass transition temperature is much higher than that of nonionomeric polyurethanes. It is shown that phosphorus-containing nonionomeric polyurethanes possess higher thermal stability in inert atmosphere than phosphorous-containing polyurethane ionomers. The onset temperature of the thermal degradation for nonionomeric polyurethanes decreases considerably with an increase in the content of polyphosphates. Polyurethane ionomers synthesized using phospholipids feature a lower thermal stability than polyurethanes based on amino ethers of orthophosphoric acid.

PH and thermo responsive aliphatic tertiary amine chromophore hyperbranched poly(amino ether ester)s from oxa‐Michael addition polymerization

AbstractIn this research, we developed a novel and facile strategy to prepare aliphatic tertiary amine chromophore hyperbranched poly(amino ether ester)s with pH and thermo responsiveness via phosphazene base (t‐BuP2) catalyzed oxa‐Michael addition polymerization of triethanolamine with ethylene glycol diacrylate at room temperature. UV–vis and fluorescence analyses results showed that the tertiary amine at branching point for hyperbranched poly(amino ether ester)s is very important to retain strong blue fluorescence of tertiary amine chromophore. Moreover, the hyperbranched poly(amino ether ester)s exhibit an aggregation caused quenching (ACQ) fluorescence, solvent induced red‐shifted emission, molecular weight, and temperature dependent emission characters. More interestingly, the hyperbranched poly(amino ether ester)s show extreme acid induced quenching fluorescence phenomenon, and also display good water solubility, specific recognition of Fe3+ ion, low cytotoxicity, and bright cell imaging, which could serve as a microenvironment‐responding fluorescent probe for application in chemical sensing, cell imaging, drug delivery, or disease diagnostics. This research provides a versatile method for the preparation of stimuli‐responsive aliphatic tertiary amine chromophore polymers, and supplies ideas for researchers to explore other unconventional fluorescent polymers for application.

Polyurethanes Based on Modified Amino Ethers of Boric Acid

Using modified amino ethers of boric acid, porous polyurethanes are synthesized, the porous morphology of which is due to the peculiarities of the hyperbranched macromolecular architecture of amino ethers of boric acid. A change in the structure of amino ethers of boric acid by the introduction of terminal bulky substituents with hydroxyl groups contributes to a change in the size and pore size distribution of polyurethanes based on amino ethers of boric acid. It is shown that one of the reasons for the heat-sensitive vapor permeability of porous polyurethanes is the hydrophilic nature of the pore surface. Film samples of porous polyurethanes have proven to be an effective substrate for the targeted cultivation of connective tissue at the cellular level.

Computational Insight into 1,2-Diamine, -Diether, and -Amino Ether Chiral Ligand-Mediated Carbolithiation: A Case of Enantioinduction Reversal.

trans-1,2-Cyclohexanediamine, -diether, and -amino ether were compared as chiral inducers in the asymmetric intramolecular carbolithiation of olefinic aryllithiums. Switching from diamine to ethereal ligands inverts the sense of asymmetric induction. This reversal of stereoselectivity was investigated through density functional theory calculations. High enantioselectivities observed with diether and amino ether ligands arise from favorable weak interactions between the ligand and the substrate. The relative efficiency of the three ligands and sense of stereoinduction for the most efficient diether and amino ether ligands prove to be foreseeable by modeling the reaction with the parent achiral 1,2-bidentate additives and comparing the diastereomeric transition states stemming from the two half-chair conformations of their lithium chelate.

Synthesis of 2-methoxy-3-(thiophen-2-ylmethyl)quinoline containing amino carbinols as antitubercular agents.

We have designed and synthesized 2-methoxy-3-(thiophen-2-ylmethyl)quinoline containing amino carbinols as possible anti-tubercular agents to combat the disease. These molecules were synthesized by tethering amino ether linkage with hydroxyl group to diarylquinoline skeleton; hydroxyl and amine chains were engrafted on diaryl ring. They were evaluated against strain (H37Ra) of Mycobacterium tuberculosis and most of compounds showed in vitro antitubercular activity. Two compounds having diaryl quinoline hydroxyl amino ether scaffold and three compounds having diaryl amino alkyl carbinol core showed activities at 6.25μg/mL. This study explores diaryl carbinol prototype as inhibitor against Mycobacterium tuberculosis.

Facile Synthesis of Oxime Amino Ethers via Lewis Acid Catalyzed SN2-Type Ring Opening of Activated Aziridines with Aryl Aldehyde Oximes

A simple strategy to access a wide range of substituted oxime amino ethers in good to high yields via Lewis acid catalyzed SN2-type ring opening of activated aziridines with aryl aldehyde oximes is reported.

Evaluation of the weathering resistance of waterborne acrylic- and alkyd-based coatings containing HALS, UV absorber, and bark extracts on wood surfaces

In this study, tree bark extracts were assessed as functional additives to provide protection in waterborne acrylic- and alkyd-based coatings. Tree bark extracts acted as natural photostabilizers and inhibited UV degradation with high UV absorption capacity. The coating systems comprising bark extracts were compared to the control coating groups comprising ultraviolet light absorbers (UVA) of the hydroxyphenyl-s-triazine (HPT) for acrylic and nonbasic amino ether (NOR) hindered amine light stabilizers (HALS) for alkyd. Scots pine surfaces coated with acrylic and alkyd coatings were exposed to artificial weathering for 2016 h. Three different trees (maritime pine, alder and Calabrian pine) with high antioxidant activity and phenol content were used for this purpose. The chemical structure of acrylic and alkyd coating systems was also examined using ATR–FTIR spectroscopy. The weathering resistance of coating systems containing extracts was evaluated in terms of their color changes and surface roughness through macroscopic evaluation, and they were compared to commercial UV absorber. The lowest color change was observed in the alkyd-based coatings with the bark extract. For the alkyd coatings, the color change (∆E) in the control samples was 24.85, whereas it was found to be 4.68, 5.92 and 7.80 in the test samples containing Calabrian pine, maritime pine and alder bark, respectively. However, color stabilization of the acrylic coatings with UV absorber was found to be much better than the acrylic coatings with extracts. The alkyd coating systems with extracts did not exhibit the same performance for surface roughness. The alkyd coating with the UV absorber provided a smoother surface than that with bark extracts. The acrylic coatings with alder and maritime extracts provided the best results. Acrylic coating may be compatible with (Calabrian) bark extracts. According to the obtained results, it was seen that tree bark extracts in wood coating systems have a potential to substitute commercial UV absorbers as a natural product.