Amine Component Research Articles

Aniline-Promoted Cyclization-Replacement Cascade Reactions of 2-Hydroxycinnamaldehydes with Various Carbonic Nucleophiles through In Situ Formed N,O-Acetals.

In this study, we report the harnessing of new reactivity of N,O-acetals in an aminocatalytic fashion for organic synthesis. Unlike widely used strategies requiring the use of acids and/or elevated temperatures, direct replacement of the amine component of the N,O-acetals by carbon-centered nucleophiles for C-C bond formation is realized under mild reaction conditions. Furthermore, without necessary preformation of the N,O-acetals, an amine-catalyzed in situ formation of N,O-acetals is developed. Coupling both reactions into a one-pot operation enables the achievement of a catalytic process. We demonstrate the employment of simple anilines as promoters for the cyclization-substitution cascade reactions of trans-2-hydroxycinnamaldehydes with various carbonic nucleophiles including indoles, pyrroles, naphthols, phenols, and silyl enol ethers. The process offers an alternative approach to structurally diverse, "privileged" 2-substituted 2H-chromenes. The synthetic power of the new process is furthermore shown by its application in a 2-step synthesis of the natural product candenatenin E and for the facile installation of 2-substituted 2H-chromene moieties into biologically active indoles.

Synthesis of new amines for enhanced carbon dioxide (CO2) capture performance: The effect of chemical structure on equilibrium solubility, cyclic capacity, kinetics of absorption and regeneration, and heats of absorption and regeneration

Abstract This work focused on the synthesis of new tertiary amines by varying the alkyl chain length with/without hydroxyl group in the structure. The effect of chemical structure of newly synthesized tertiary amines; 4-(dimethylamino)-2-butanol (DMAB), 4-(dipropylamino)-2-butanol (DPAB), 4-(dibutylamino)-2-butanol (DBAB), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB) were evaluated based on CO 2 equilibrium solubility and cyclic capacity, as well as rates and heats of CO 2 absorption and regeneration. The results showed that three amines (i.e. DMAB, HEMAB and HEEAB) had the highest CO 2 absorption capacity (0.88, 0.44 and 0.68 mol CO 2 /mol amine at 313 K temperature and 15 kPa CO 2 partial pressure), and cyclic capacity (0.52, 0.26 and 0.40 at 313–353 K temperature range, 15 kPa CO 2 partial pressure). These amines also had fast CO 2 absorption rate (0.082, 0.111 and 0.142 mol CO 2 /min) and CO 2 regeneration rate (0.512, 0.452 and 0.295 mol CO 2 /min) while maintaining low heat of CO 2 absorption (−34.17, −56.21 and −69.79 kJ/mol CO 2 ) and heat input of CO 2 regeneration (39.73, 60.48 and 72.44 kJ/mol CO 2 ). Based on these results, DMAB, HEMAB, and HEEAB can be considered to be promising amine components for blending for a post combustion CO 2 capture process.

ChemInform Abstract: Enantioselective Synthesis of BE Ring Analogues of Methyllycaconitine.

Abstract The enantioselective synthesis of decahydroquinolines mimicking the BE rings of methyllycaconitine (MLA) is reported. The analogues were synthesised via a one-pot cyclisation using ethyl α-(bromomethyl)acrylate, (R)-1-phenylethanamine and cyclohexanone to form chiral octahydroquinolines which can be selectively hydrogenated to form the 3-substituted-decahydroquinolines with the same stereochemistry found in MLA. The amine and ketone components in the one-pot reaction can also be altered to provide access to structurally related heterocycles.

Ugi Four-Component Assembly Process: An Efficient Approach for One-Pot Multifunctionalization of Nanographene Oxide in Water and Its Application in Lipase Immobilization

Graphene-based materials are revealing the leading edge of advanced technology for their exceptional physical and chemical properties. Chemical manipulation on graphene surface to tailor its unique properties and modify atomic structures is being actively pursued. Therefore, the discovery of robust and general protocols to anchor active functionality on graphene basal plane is still of great interest. Multicomponent reactions promise an enormous level of interest due to addressing both diversity and complexity in combinatorial synthesis, in which more than two starting compounds react to form a product derived from entire inputs. In this article, we present the first covalent functionalization route beginning with carboxylated-graphene oxide through Ugi four-component assembly process (Ugi 4-CAP), in which amine, aldehyde, isocyanide, and acid components come together in a one-pot reaction to generate hydrophobic-, hydrophilic-, or amiphiphilic multifunctionalized graphene composites. Investigation on the...

Carbon‐Nanotube‐Mediated Electrochemical Transition in a Redox‐Active Supramolecular Hydrogel Derived from Viologen and an l‐Alanine‐Based Amphiphile

A two-component hydrogelator (16-A)2 -V(2+) , comprising an l-alanine-based amphiphile (16-A) and a redox-active viologen based partner (V(2+) ), is reported. The formation the hydrogel depended, not only on the acid-to-amine stoichiometric ratio, but on the choice of the l-amino acid group and also on the hydrocarbon chain length of the amphiphilic component. The redox responsive property and the electrochemical behavior of this two-component system were further examined by step-wise chemical and electrochemical reduction of the viologen nucleus (V(2+) /V(+) and V(+) /V(0) ). The half-wave reduction potentials (E1/2 ) associated with the viologen ring shifted to more negative values with increasing amine component. This indicates that higher extent of salt formation hinders reduction of the viologen moiety. Interestingly, the incorporation of single-walled carbon nanotubes in the electrochemically irreversible hydrogel (16-A)2 -V(2+) transformed it into a quasi-reversible electrochemical system.

ChemInform Abstract: Highly Diastereoselective Synthesis of Imidazolidine‐Dispirooxindoles via Three‐Component [3 + 2] Cycloadditions of Isatins, 2‐(Aminomethyl)pyridine and Isatin‐Based Imines.

AbstractNotably, benzylamine as amine component does not react.

Phosphorylation of aminomethylated derivatives of 2,7-dihydroxynaphthalenes

Phosphorylation of 2,7-dihydroxynaphthalene derivatives, containing different amine components was performed by full amides of phosphorous acid. A substantial effect of the intramolecular hydrogen bond on the process of phosphorylation was shown. Cyclophosphorylation was performed and principal possibility of the synthesis of naphthophosphacrownaphanes having aminomethyl linkers was shown. Mannich aminomethylation of naphthophosphacyclophanes was found to be impossible.

Versatile Protecting-Group Free Tetrazolomethane Amine Synthesis by Ugi Reaction.

The use of ammonia in the Ugi reaction is often problematic due to low yields and multiple side reactions. Here, we report the use of ammonia in the tetrazole Ugi variation providing a clean, good-to-high yielding reaction, especially with ketones as oxo components. The scope and limitations of this reaction and a structure-reactivity relationship are provided by performing >85 reactions. The primary amine component of the α-amino tetrazole is a versatile starting material for further reactions.

Synthesis of 2,3‐Disubstituted Quinazolinone Derivatives through Copper Catalyzed C–H Amidation Reactions

AbstractThe synthesis of quinazolinone derivatives was achieved from 2‐iodobenzamide derivatives and various benzylamines, allylamine, and cinnamylamine derivatives through a one‐pot copper‐catalyzed reaction. In this reaction, the amine component (benzylamine/allylamine/cinnamylamine) is N‐arylated with 2‐iodobenzamide derivatives through Ullman coupling, followed by an intramolecular C–H amidation in the presence of copper catalyst.

Linker design for the modular assembly of multifunctional and targeted platinum(ii)-containing anticancer agents.

A versatile and efficient modular synthetic platform was developed for assembling multifunctional conjugates and targeted forms of platinum-(benz)acridines, a class of highly cytotoxic DNA-targeted hybrid agents. The synthetic strategy involved amide coupling between succinyl ester-modified platinum compounds (P1, P2) and a set of 11 biologically relevant primary and secondary amines (N1-N11). To demonstrate the feasibility and versatility of the approach, a structurally and functionally diverse range of amines was introduced. These include biologically active molecules, such as rucaparib (a PARP inhibitor), E/Z-endoxifen (an estrogen receptor antagonist), and a quinazoline-based tyrosine kinase inhibitor. Micro-scale reactions in Eppendorf tubes or on 96-well plates were used to screen for optimal coupling conditions in DMF solution with carbodiimide-, uronium-, and phosphonium-based compounds, as well as other common coupling reagents. Reactions with the phosphonium-based coupling reagent PyBOP produced the highest yields and gave the cleanest conversions. Furthermore, it was demonstrated that the chemistry can also be performed in aqueous media and is amenable to parallel synthesis based on multiple consecutive reactions in DMF in a "one-tube" format. In-line LC-MS was used to assess the stability of the conjugates in physiologically relevant buffers. Hydrolysis of the conjugates occurs at the ester moiety and is facilitated by the aquated metal moiety under low-chloride ion conditions. The rate of ester cleavage greatly depends on the nature of the amine component. Potential applications of the linker technology are discussed.

Enantioselective synthesis of BE ring analogues of methyllycaconitine

The enantioselective synthesis of decahydroquinolines mimicking the BE rings of methyllycaconitine (MLA) is reported. The analogues were synthesised via a one-pot cyclisation using ethyl α-(bromomethyl)acrylate, (R)-1-phenylethanamine and cyclohexanone to form chiral octahydroquinolines which can be selectively hydrogenated to form the 3-substituted-decahydroquinolines with the same stereochemistry found in MLA. The amine and ketone components in the one-pot reaction can also be altered to provide access to structurally related heterocycles.

ChemInform Abstract: Aminocarbonylation of Aryl Tosylates to Carboxamides.

The palladium - catalyzed aminocarbonylation of aryl tosylates with amines is reported. Suitable conditions were identified by high throughput reaction screening and then further optimized. The substrate scope of the reaction with respect to the aryl tosylate component and the amine component are reported. Competitive aminolysis of the aryl tosylates to afford the amine toluenesulfonamides and the phenol was not observed.

Quantitative determination of amines used in post-combustion CO2 capture process by ion chromatography

In post-combustion CO2 capture (PCCC) with amine-based solvents, determining the amount of amine components present in the liquid phase is essential. The quantification of the solvent should be fast, accurate and simple. Toward this direction, suppressed cation exchange chromatography can be a powerful tool for the determination of the amines and their degradation products. In this paper, validated methods for 12 commercial amines and 2 degradation products were developed. The amines included primary, secondary and tertiary alkanolamines, polyamines as well as cyclic amines. Amines were determined with the chromatographic system Dionex Thermo Scientific ICS-5000 with CS19 as column and CG19 as guard column. A thermoscientific conductivity detector was used for identifying the various analytes. The validated methods were used for quantitative analysis and the coefficient of determination was greater than 0.99. Moreover, applications for determination of amines from pilot plant studies, trace analysis of cationic species and analysis of degraded samples are presented. Finally, it was shown that amine concentrations can be determined fast and accurate with CS19 without any special sample preparation.

Vegetable oil-based polybenzoxazine derivatives coatings on Zn–Mg–Al alloy coated steel

Based on environmentally friendly (bio-based) precursor materials a new class of benzoxazine derivatives was synthesized using phenolated high oleic sunflower oil as phenol component and either aniline or 1,6-diaminohexane as amine components. Hydrophobic and dense poly(benzoxazine) coatings on Zn–Mg-Al alloy coated steel were obtained after spin-coating or air-brush type spray coating by crosslinking during a heat treatment step. The poly(benzoxazine)-coated ZM-steel samples showed an anodic shift of the open circuit potential as well as the break-through potential. Using an automatic scanning droplet cell the impact of the polymer film thickness on corrosion protection was evaluated.

Innovative approach for the synthesis of benzoxazine-modified montmorillonite

The synthesis of a benzoxazine (BZ) monomer inside the montmorillonite (MT) layers was done using a diamino-modified MT as the amine component, phenol, and formaldehyde. The formation of the BZ rings within the MT layers was investigated by thermogravimetric analysis, X-ray photoelectron spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction, this being enhanced when dioxane was used as the solvent. The morphology of the hybrid BZ monomer was investigated by scanning electron microscopy.

Aminocarbonylation of aryl tosylates to carboxamides.

The palladium - catalyzed aminocarbonylation of aryl tosylates with amines is reported. Suitable conditions were identified by high throughput reaction screening and then further optimized. The substrate scope of the reaction with respect to the aryl tosylate component and the amine component are reported. Competitive aminolysis of the aryl tosylates to afford the amine toluenesulfonamides and the phenol was not observed.

Aromatic amine contents, component distributions and risk assessment in sludge from 10 textile-dyeing plants

Aromatic amines (AAs), which are components of synthetic dyes, are recalcitrant to the wastewater treatment process and can accumulate in sludge produced by textile-dyeing, which may pose a threat to the environment. A comprehensive investigation of 10 textile-dyeing plants was undertaken in Guangdong Province in China. The contents and component distributions of AAs were evaluated in this study, and a risk assessment was performed. The total concentrations of 14 AAs (Σ14 AAs) varied from 11μgg−1dw to 82.5μgg−1dw, with a mean value of 25μgg−1dw. The component distributions of AAs were characterized by monocyclic anilines, of which 2-methoxy-5-methylaniline and 5-nitro-o-toluidine were the most dominant components. The risk quotient (RQ) value was used to numerically evaluate the ecological risk of 14 AAs in the environment. The result showed that the 14 AAs contents in textile-dyeing sludge may pose a high risk to the soil ecosystem after being discarded on soil or in a landfill.

Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis.

ConspectusWhile the use of visible light to drive chemical reactivity is of high importance to the development of environmentally benign chemical transformations, the concomitant use of a stoichiometric electron donor or acceptor is often required to steer the desired redox behavior of these systems. The low-cost and ubiquity of tertiary amine bases has led to their widespread use as reductive additives in photoredox catalysis. Early use of trialkylamines in this context was focused on their role as reductive excited state quenchers of the photocatalyst, which in turn provides a more highly reducing catalytic intermediate.In this Account, we discuss some of the observations and thought processes that have led from our use of amines as reductive additives to their use as complex substrates and intermediates for natural product synthesis. Early attempts by our group to construct key carbon–carbon bonds via free-radical intermediates led to the observation that some trialkylamines readily behave as efficient hydrogen atom donors under redox-active photochemical conditions. In the wake of in-depth mechanistic studies published in the 1970s, 1980s and 1990s, this understanding has in turn allowed for a systematic approach to the design of a number of photochemical methodologies through rational tuning of the amine component. Minimization of the C–H donicity of the amine additive was found to promote desired C–C bond formation in a number of contexts, and subsequent elucidation of the amine’s redox fate has sparked a reevaluation of the amine’s role from that of reagent to that of substrate.The reactivity of tertiary amines in these photochemical systems is complex, and allows for a number of mechanistic possibilities that are not necessarily mutually exclusive. A variety of combinations of single-electron oxidation, C–H abstraction, deprotonation, and β-scission result in the formation of reactive intermediates such as α-amino radicals and iminium ions. These processes have been explored in depth in the photochemical literature and have resulted in a firm mechanistic grasp of the behavior of amine radical cations in fundamental systems. Harnessing the synthetic potential of these transient species represents an ongoing challenge for the controlled functionalization of amine substrates, because these mechanistic possibilities may result in undesired byproduct formation or substrate decomposition. The presence of tertiary amines in numerous alkaloids, pharmaceuticals, and agrochemicals lends credence to the potential utility of this chemistry in natural product synthesis, and herein we will discuss how these transformations might be controlled for synthetic purposes.

Phenolated Oleic Acid Based Polybenzoxazine Derivatives as Corrosion Protection Layers.

Benzoxazine derivatives were synthesized using phenolated methyl oleate and either aniline, 1,6-diaminohexane, or 4,4'-diaminodiphenylmethane, respectively, as amine components. Polymerization of the benzoxazine derivatives led to the formation of hydrophobic and dense coatings on Zn-Mg-Al alloy coated steel sheets for passive corrosion protection. The polybenzoxazine coatings which are formed by crosslinking during a heat-treatment step invoked a substantial anodic shift of the open-circuit potential as well as the breakthrough potential in potentiodynamic measurements. The proposed polybenzoxazine derivatives pave the way for a new type of passive polymer protection system based on sustainably obtained precursor components.

Bis-triarylamine with a cyclometalated diosmium bridge: A multi-stage redox-active system

A tetra(pyrid-2-yl)-pyrazine-bridged cyclometalated diosmium complex 1(PF6)2 with two distal redox-active organic amine substituents has been synthesized and characterized. This complex displays four consecutive and separated anodic redox waves at +0.24, +0.38, +0.64, and +0.71 V vs. Ag/AgCl. Upon stepwise oxidation, four-step absorption spectral changes in the visible to near-infrared region have been observed. The different redox states of 1 (12+ through 16+) can be distinguished by the significantly different absorption spectra in the visible and near-infrared region. DFT calculations of 13+ show that the spin is delocalized on both osmium–amine components.