Tertiary Aliphatic Amines Research Articles

Enantioselective Alkylation of Primary C(sp3)-H Bonds in N-Methyl Tertiary Amine Enabled by Iridium Complex of Axially Chiral β-Aryl Porphyrins.

A fine-tuning of enantioselective carbene insertion into primary C(sp3)-H bonds has been realized in challenging substrates, such as N-methyl unblocked aromatic and non-deactivated aliphatic tertiary amines, in which sterically demanding β-axially chiral iridium porphyrin catalysts play a crucial role. This primary C(sp3)-H alkylation with diazo compounds affords a series of β-chiral tertiary amines in high yields with excellent enantioselectivities. Notably, the protocol was successfully applied to the postmodification of chiral bicuculline, yielding the desired derivative with high diastereoselectivity. This approach paves a facile way for the stereodivergent derivation of chiral alkaloid natural products featuring an N-methyl handle. In addition, a mechanism for the reaction was proposed based on deuterium experiments and an identified cationic iridium species via HRMS analysis.

Multicomponent Construction of Tertiary Alkylamines by Photoredox/Nickel-Catalyzed Aminoalkylation of Organohalides.

Tertiary alkylamines are privileged structural motifs widely present in natural products, pharmaceutical agents, and bioactive molecules, and their efficient synthesis has been a longstanding goal in organic chemistry. The functionalization of α-amino radicals derived from abundant precursors represents an emerging approach to accessing alkylamines, but application of this strategy to obtain tertiary alkylamines remains challenging. Here, we show that dual photoredox/nickel catalysis enables aminoalkylation of organohalides (sp2- and sp3-hybridized) in combination with secondary alkylamines and aldehydes. The multicomponent process proceeds through selective generation of α-amino radicals from the reduction of in situ-generated iminium ions by photoredox catalysis, followed by nickel-catalyzed cross-coupling to build a wide array of functionally diverse tertiary alkylamines. This strategy could also be extended to unprecedented four-component reactions and their asymmetric variants to deliver enantioenriched α-aryl-substituted γ-amino acid derivatives. Taken together, this work offers a streamlined synthetic route to aliphatic tertiary amines.

Selective cleavage of Csp3–N bonds in aliphatic tertiary amines enabled by difluorocarbene to access esters and thioethers

Presented herein is a series of C–X (X ​= ​O, S) couplings for the synthesis of esters and thioethers via difluorocarbene-promoted selective Csp3–N bond cleavage between tertiary amines and carboxylic acids or thiols. In those reactions, difluorocarbene plays an important role for generating quaternary ammonium salts and thus efficiently activates the Csp3–N bonds in aliphatic tertiary acyclic amines. The developed reaction does not require any transition metal catalyst and features broad substrate scope, good functional group compatibility and ease of execution with more than 70 examples in total.

Direct synthesis of branched amines enabled by dual-catalyzed allylic C─H amination of alkenes with amines.

Direct conversion of hydrocarbons into amines represents an important and atom-economic goal in chemistry for decades. However, intermolecular cross-coupling of terminal alkenes with amines to form branched amines remains extremely challenging. Here, a visible-light and Co-dual catalyzed direct allylic C─H amination of alkenes with free amines to afford branched amines has been developed. Notably, challenging aliphatic amines with strong coordinating effect can be directly used as C─N coupling partner to couple with allylic C─H bond to form advanced amines with molecular complexity. Moreover, the reaction proceeds with exclusive regio- and chemoselectivity at more steric hinder position to deliver primary, secondary, and tertiary aliphatic amines with diverse substitution patterns that are difficult to access otherwise.

Eco-Friendly Approach for the Recovery of Lactic Acid by Complex Extraction.

To meet the growing demand for high-purity lactic acid (LA) for biocompatible and biodegradable polymers, LA recovery by green techniques has been attracting the attention. This study focuses on the evaluation of vegetable oils as organic phase diluents in complex extraction of LA with an aliphatic tertiary amine extractant, trioctylamine (TOA). Eight vegetable oils were tested, and their performances were evaluated individually and compared with those obtained using 1-octanol. Extraction yields with these oils were similar; however, efficiencies with safflower oil (SFO) were slightly higher than those obtained with other oils tested. Efficiency with SFO + TOA varied inversely with temperature and pH; however, it increased with higher LA and TOA concentrations. Within the ranges of parameters investigated, the highest yield in SFO was 66% and was achieved at the highest TOA (1.0 M) and LA (1.5 M) concentrations. The efficiency obtained in 1-octanol under the identical conditions was 76%. Thus, the yields obtained with SFO + TOA and 1-octanol + TOA were comparable under most of the conditions tested, especially at the higher LA concentrations, which is preferred for commercial production. Following that, >99% of the LA was transferred from the organic phase to the (second) aqueous phase using NaOH (1.0 M) as a stripping agent. The organic phase was tested in subsequent extractions, and yields comparable to those obtained in the first uses were achieved. This study demonstrated that vegetable oils have the potential to be used as organic phase diluents during complex extraction of LA.

Sulfatobetaine Synthesis from Epoxides and Tertiary Amine‐Sulfur Trioxide Complexes

AbstractThe sulfatobetaine formation from epoxides and tertiary amine‐sulfur trioxide complexes was studied. It was revealed that heterocyclic tertiary amine‐sulfur trioxide complexes being the most electrophilic and reactive complexes produce sulfatobetaines in 15.5–62.6 % isolation yields, the aliphatic tertiary amine sulfur‐trioxide complexes failed to form the expected products. The presence of the amine taken in 5‐fold excess improves the isolation yields of the sulfatobetaines (52–100 %).

Synthesis of oligoimides with terminal nadic groups in the presence of a new cyclizing system methyltriethoxysilane — tertiary aliphatic amine

Synthesis of oligoimides with terminal nadic groups in the presence of a new cyclizing system methyltriethoxysilane — tertiary aliphatic amine

X‐Ray Crystallography and Antimicrobial Activity of Synthetic Cyanoguanidinophenytoin Cocrystals

AbstractA novel series of 1 : 1 cocrystals of 2‐cyanoguanidinophenytoin (CNG‐DPH) with primary, secondary, and tertiary aliphatic amines has been presented through this work. The antimicrobial activities of all new CNG‐DPH‐amine cocrystals were studied. The existence of cocrystals has been proven through crystal structure results. The 5‐Oxo‐4,4‐diphenylimidazolidin‐2‐ylidenecyanamide‐piperidine cocrystal (10) is located in an orthorhombic crystal system, and the cocrystal is connected via the N−H−N hydrogen bond between the cyanide group and the piperidine molecule. Hirshfeld surface analysis authenticated supramolecular contacts. Ring puckering analysis revealed a chair stereochemistry at the 6‐membered piperidine. The crystal packing has been stabilized through intermolecular forces, hydrogen bonds, and interactions within the gravity center of rings (Cg). The antimicrobial activities of the newly synthesized compounds were only effective against Gram‐positive bacteria, demonstrating that the antibacterial spectrum of these compounds was restricted. In vitro cytotoxicity of the synthesized cocrystals was assessed in normal cells, giving the highest half‐maximal inhibitory concentration (IC50) ratio (637.63 μg/ml) and the lowest value (181.98 μg/ml).

Self-reporting and Biodegradable Thermosetting Solid Polymer Electrolyte.

To date, significant efforts have been dedicated to improve their ionic conductivity, thermal stability, and mechanical strength of solid polymer electrolytes (SPEs). However, direct monitoring of physical and chemical changes in SPEs is still lacking. Moreover, existing thermosetting SPEs are hardly degradable. Herein, by overcoming the limitation predicted by Flory theory, self-reporting and biodegradable thermosetting hyperbranched poly(β-amino ester)-based SPEs (HPAE-SPEs) are reported. HPAE is successfully synthesized through a well-controlled "A2+B4" Michael addition strategy and then crosslinked it in situ to produce HPAE-SPEs. The multiple tertiary aliphatic amines at the branching sites confer multicolour luminescence to HPAE-SPEs, enabling direct observation of its physical and chemical damage. After use, HPAE-SPEs can be rapidly hydrolysed into non-hazardous β-amino acids and polyols via self-catalysis. Optimized HPAE-SPE exhibits an ionic conductivity of 1.3×10-4 S/cm at 60 °C, a Na+ transference number ( ) of 0.67, a highly stable sodium plating-stripping behaviour and a low overpotential of ≈190 mV. This study establishes a new paradigm for developing SPEs by engineering multifunctional polymers. The self-reporting and biodegradable properties would greatly expand the scope of applications for SPEs.

Self‐reporting and Biodegradable Thermosetting Solid Polymer Electrolyte

AbstractTo date, significant efforts have been dedicated to improve their ionic conductivity, thermal stability, and mechanical strength of solid polymer electrolytes (SPEs). However, direct monitoring of physical and chemical changes in SPEs is still lacking. Moreover, existing thermosetting SPEs are hardly degradable. Herein, by overcoming the limitation predicted by Flory theory, self‐reporting and biodegradable thermosetting hyperbranched poly(β‐amino ester)‐based SPEs (HPAE‐SPEs) are reported. HPAE is successfully synthesized through a well‐controlled “A2+B4” Michael addition strategy and then crosslinked it in situ to produce HPAE‐SPEs. The multiple tertiary aliphatic amines at the branching sites confer multicolour luminescence to HPAE‐SPEs, enabling direct observation of its physical and chemical damage. After use, HPAE‐SPEs can be rapidly hydrolysed into non‐hazardous β‐amino acids and polyols via self‐catalysis. Optimized HPAE‐SPE exhibits an ionic conductivity of 1.3×10−4 S/cm at 60 °C, a Na+ transference number ( ) of 0.67, a highly stable sodium plating‐stripping behaviour and a low overpotential of ≈190 mV. This study establishes a new paradigm for developing SPEs by engineering multifunctional polymers. The self‐reporting and biodegradable properties would greatly expand the scope of applications for SPEs.

Expedient deaminative phosphorylation and sulfonylation of benzylic tertiary amines enabled by difluorocarbene

A deaminative functionalization of aliphatic tertiary amines via the cleavage of C(sp3)–N bonds under transition metal-free conditions was disclosed, which goes through SN2 reaction with various phosphorus and sulfur nucleophiles.

Dual Catalysis of Gold Nanoclusters: Photocatalytic Cross-Dehydrogenative Coupling by Cooperation of Superatomic Core and Molecularly Modified Staples.

Thiolate-protected gold nanoclusters (AuNCs) have attracted significant attention as nano-catalysts, revealing a superatomic core and gold-thiolate staples as distinct structural units. Here, we demonstrate the unprecedented dual catalytic activity of thiolate-protected [Au25 (SR)18 ]- nanoclusters, involving both photosensitized 1 O2 generation by the Au13 superatomic core and catalytic carbon-carbon bond formation facilitated by Au2 (SR)3 staples. This synergistic combination of two different catalytic units enables efficient cross-dehydrogenative coupling of terminal alkynes and tertiary aliphatic amines to afford propargylamines in high yields of up to 93 %. Mixed-ligand AuNCs bearing both thiolate and alkynyl ligands revealed the intermediacy of the alkynyl-exchanged AuNCs toward both photosensitization and C-C bond-forming catalytic cycles. Density functional theory calculations also supported the intermediacy of the alkynyl-exchanged AuNCs. Thus, the use of ligand-protected metal nanoclusters has enabled the development of an exceptional multifunctional catalyst, wherein distinct nanocluster components facilitate cooperative photo- and chemo-catalysis.

Dual Catalysis of Gold Nanoclusters: Photocatalytic Cross‐Dehydrogenative Coupling by Cooperation of Superatomic Core and Molecularly Modified Staples**

AbstractThiolate‐protected gold nanoclusters (AuNCs) have attracted significant attention as nano‐catalysts, revealing a superatomic core and gold‐thiolate staples as distinct structural units. Here, we demonstrate the unprecedented dual catalytic activity of thiolate‐protected [Au25(SR)18]− nanoclusters, involving both photosensitized 1O2 generation by the Au13 superatomic core and catalytic carbon‐carbon bond formation facilitated by Au2(SR)3 staples. This synergistic combination of two different catalytic units enables efficient cross‐dehydrogenative coupling of terminal alkynes and tertiary aliphatic amines to afford propargylamines in high yields of up to 93 %. Mixed‐ligand AuNCs bearing both thiolate and alkynyl ligands revealed the intermediacy of the alkynyl‐exchanged AuNCs toward both photosensitization and C−C bond‐forming catalytic cycles. Density functional theory calculations also supported the intermediacy of the alkynyl‐exchanged AuNCs. Thus, the use of ligand‐protected metal nanoclusters has enabled the development of an exceptional multifunctional catalyst, wherein distinct nanocluster components facilitate cooperative photo‐ and chemo‐catalysis.

PH-Responsive Near-Infrared Emitting Gold Nanoclusters.

Near-infrared (NIR) fluorophores with pH-responsive properties suggest merits in biological analyses. This work establishes a general and effective method to obtain pH-responsive NIR emissive gold nanoclusters by introducing aliphatic tertiary amine (TA) groups into the ligands. Computational study suggests that the pH-responsive NIR emission is associated with electronic structure change upon protonation and deprotonation of TA groups. Photo-induced electron transfer between deprotonated TA groups and the surface Au-S motifs of gold nanoclusters can disrupt the radiative transitions and thereby decrease the photoluminescence intensity in basic environments (pH=7-11). By contrast, protonated TA groups curb the electron transfer and restore the photoluminescence intensity in acidic environments (pH=4-7). The pH-responsive NIR-emitting gold nanoclusters serve as a specific and sensitive probe for the lysosomes in the cells, offering non-invasive emissions without interferences from intracellular autofluorescence.

PH‐Responsive Near‐Infrared Emitting Gold Nanoclusters

AbstractNear‐infrared (NIR) fluorophores with pH‐responsive properties suggest merits in biological analyses. This work establishes a general and effective method to obtain pH‐responsive NIR emissive gold nanoclusters by introducing aliphatic tertiary amine (TA) groups into the ligands. Computational study suggests that the pH‐responsive NIR emission is associated with electronic structure change upon protonation and deprotonation of TA groups. Photo‐induced electron transfer between deprotonated TA groups and the surface Au‐S motifs of gold nanoclusters can disrupt the radiative transitions and thereby decrease the photoluminescence intensity in basic environments (pH=7–11). By contrast, protonated TA groups curb the electron transfer and restore the photoluminescence intensity in acidic environments (pH=4–7). The pH‐responsive NIR‐emitting gold nanoclusters serve as a specific and sensitive probe for the lysosomes in the cells, offering non‐invasive emissions without interferences from intracellular autofluorescence.

An investigation to compare the shear strength of the adhesive joint of unidirectional CFRP after KrF excimer laser treatment in normal atmosphere, argon and underwater environments

Unidirectional CFRP was treated by KrF laser in normal atmosphere, argon and underwater environments, before adhesive bonding. KrF laser removed the top resin layer and exposed the carbon fibres. Porosity and holes were generated around exposed carbon fibres after argon environment treatments and flakes-like-surface-structure was generated after underwater treatments with two-step method. KrF laser treatments increased Sq and Sdr values. Sdr was more influential for adhesive joint shear strength. These laser treatments in all environments transformed secondary and tertiary aliphatic amines to primary and secondary aliphatic amines, respectively. SLSS study confirmed that the highest shear strength of 35.78 MPa which was 45% higher than the untreated joint, was achieved after underwater treatment. Normal atmosphere and argon environment treatments resulted in 31.74 and 31.95 MPa, respectively. Adhesive failure which occurred after argon environment treatments, reduced after normal atmosphere treatments. Underwater treatments resulted in cohesive failure and thin layer cohesive failure.

Structural features localizing the ferroptosis inhibitor GIF-2197-r to lysosomes.

We previously reported that N,N-dimethylaniline derivatives are potent ferroptosis inhibitors. Among them, the novel aminoindan derivative GIF-2197-r (the racemate of GIF-2115 (R-form) and GIF-2196 (S-form)) is effective at a concentration of 0.01 μM due to its localization to lysosomes and ferrous ion coordination capacity. The current study demonstrates that the aliphatic tertiary amine moiety of GIF-2197-r is responsible for lysosomal localization. Although N,N-dimethylaniline derivatives cannot form chelate structures with Fe2+, density functional theory computation demonstrates that they can form stable monodentate complexes with a hydrated ferrous ion, likely due to the highly electron-rich nature of the (dialkylamino)phenyl ring. Furthermore, the results suggest that the aliphatic tertiary amine moiety contributes to stabilizing the complexation. These findings could prove useful for developing improved lysosomotropic ferroptosis inhibitors for neurodegenerative diseases.

Effects of Trimethylamine and Trimethylamine Oxide on Human Serum Albumin Observed by Tryptophan Fluorescence and Absorbance Spectroscopies

Trimethylamine (TMA) is an aliphatic tertiary amine produced by gut microbiota, starting from dietary precursors such as L-choline, L-carnitine and betaine. TMA and its metabolite trimethylamine-N-oxide (TMAO) are elevated in the plasma of cardiovascular disease (CVD) patients. Despite extensive literature on this topic, the scientific community is still divided on which of the two molecules is responsible for the harmful effects on human health. To assess whether the plasma levels of these molecules are also modulated by interactions with macromolecules present in the plasma, the weak bonds between TMA or/and TMAO with human serum albumin (HSA) were studied via molecular docking and spectrofluorimetric assay. The impact of TMA and TMAO on HSA and low-density lipoproteins (LDL) oxidation was also evaluated. Docking analysis shows three main binding sites for TMA and two for TMAO. Spectrofluorimetric results show interactions of HSA with TMA and TMAO; a significant (p = 0.010) decrease in Trp-214 intrinsic fluorescence of HSA was measured starting from the lowest concentrations of both TMA and TMAO (3.26 nM and 29.2 nM, respectively). Furthermore, at all concentrations tested, no significant effect on the formation of carbonyls in HSA was measured (p > 0.05) in the presence of TMA or TMAO. However, 28.6 mM TMAO significantly increased (p < 0.05) the degree of oxidation of LDL, suggesting that TMAO has a pro-oxidant role on LDL.

Tuning the Photocatalytic Performance of Ruthenium(II) Polypyridine Complexes Via Ligand Modification for Visible-Light-Induced Phosphorylation of Tertiary Aliphatic Amines.

Tuning the redox potential of commonly available photocatalyst to improve the catalytic performance or expand its scope for challenging synthetic conversions is an ongoing demand in synthetic chemistry. Herein, the excited state properties and redox potential of commercially available [Ru(bpy)3 ]2+ photocatalyst were tuned by modifying the structure of the bipyridine ligands with electron-donating/withdrawing units. The visible-light-mediated photoredox phosphorylation of tertiary aliphatic amines was demonstrated under mild conditions. A series of cross-dehydrogenative coupling reactions were performed employing the RuII complexes as photocatalyst giving the corresponding α-aminophosphinoxides and α-aminophosphonates via carbon-phosphorus (C-P) bond formation.

Self-assembling Peptides with Internal Ionizable Unnatural Amino Acids: A General Approach to pH-responsive Peptide Materials.

Self-assembled peptides are an emerging family of biomaterials that show great promise for a range of biomedical and biotechnological applications. Introducing and tuning the pH-responsiveness of the assembly is highly desirable for improving their biological activities. Inspired by proteins with internal ionizable residues, we report a simple but effective approach to constructing pH-responsive peptide assembly containing unnatural ionic amino acids with an aliphatic tertiary amine side chain. Through a combined experimental and computational investigation, we demonstrate that these residues can be accommodated and stabilized within the internal hydrophobic compartment of the peptide assembly. The hydrophobic microenvironment shifts their pKa significantly from a basic pH typically found for free amines to a more biologically relevant pH in the weakly acidic range. The pH-induced ionization and ionization-dependent self-assembly and disassembly are thoroughly investigated and correlated with the biological activity of the assembly. This new approach has unique advantages in tuning the pH-responsiveness of self-assembled peptides across a large pH range in a complex biological environment. We anticipate the ionizable amino acids developed here can be widely applicable to the synthesis and self-assembly of many amphiphilic peptides with endowed pH-responsive properties to enhance their biological activities toward applications ranging from targeted therapeutic delivery to proton transport.