Search

Highly regioselective C−H alkylation reactions of tertiary anilines and tertiary alkyl amines with simple alkenes have been achieved by the use of imidazolin‐2‐iminato scandium alkyl complexes. This protocol provided an efficient and atom‐economical route to structurally diverse tertiary amine derivatives. The basic ligand, a coordinating THF in the catalyst and the substitution of alkene substrates were found to switch the regioselectivity of the C−H alkylation reactions of tertiary anilines presumably due to the generation of different types of catalytically active species or the formation of relatively stable intermediates. On the basis of the deuterium labeling experiments and KIE experiments, possible catalytical cycles were provided to understand the reaction mechanism as well as the regioselectivity. [ABSTRACT FROM AUTHOR]

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes. [ABSTRACT FROM AUTHOR]

Homocubane, a highly strained cage hydrocarbon, contains two very different positions for the introduction of a nitrogen atom into the skeleton, e. g. a position 1 exchange results in a tertiary amine whereas position 9 yields a secondary amine. Herein reported is the synthesis of 9‐azahomocubane along with associated structural characterization, physical property analysis and chemical reactivity. Not only is 9‐azahomocubane readily synthesized, and found to be stable as predicted, the basicity of the secondary amine was observed to be significantly lower than the structurally related azabicyclo[2.2.1]heptane, although similar to 1‐azahomocubane. [ABSTRACT FROM AUTHOR]

Homoleptic [L−I−L]+ iodine(I) complexes (where L is a R3R2R1N tertiary amine) were synthesized via the [L−Ag−L]+→ [L−I−L]+ cation exchange reaction. In solution, the amines form [R3R2R1N−Ag−NR1R2R3]+ silver(I) complexes, which crystallize out from solution as the meso‐[L−Ag−L]+complexes, as characterized by X‐ray crystallography. The subsequent [L−I−L]+ iodine(I) analogues were extremely reactive and could not be isolated in the solid state. Density functional theory (DFT) calculations were performed to study the Ag+−N and I+−N interaction energies in silver(I) and iodine(I) complexes, with the former ranging from −80 to −100 kJ mol−1 and latter from −260 to −279 kJ mol−1. The X‐ray crystal structures revealed Ag+⋅⋅⋅Cπ and Ag+⋅⋅⋅H−C short contacts between the silver(I) cation and flexible N‐alkyl/N‐aryl groups, which are the first of their kind in such precursor complexes. [ABSTRACT FROM AUTHOR]

Reversible hydrogen storage in the form of stable and mostly harmless chemical substances such as formic acid (FA) is a cornerstone of a fossil fuels‐free economy. In the past, we have reported a primary amine‐functionalized bifunctional iridium(III)‐PC(sp3)P pincer complex as a mild and chemoselective catalyst for the additive‐free decomposition of neat formic acid. In this manuscript, we report on the successful application of a redesigned complex bearing tertiary amine functionality as a catalyst for mild hydrogenation of CO2 to formic acid. The catalyst demonstrates TON up to 6×104 and TOF up to 1.7×104 h−1. In addition to the practical value of the catalyst, experimental and computational mechanistic studies provide the rationale for the design of improved next‐generation catalysts. [ABSTRACT FROM AUTHOR]

Organic molecules, containing one or more amine chiral centers, are very common to see in natural products and medicines. Although a large number of methods have been developed to afford enantiopure amines, most of the known approaches are limited with various reasons. For example, many methodologies start from nitrogen protected and activated substrates, which usually need multistep operations and seriously decrease the atom economy. Here we disclose a new catalytic strategy from commercial nitriles to high enantioselective α‐tertiary primary amines in up to 90 % yield and 95 % enantiomeric excess. This transformation firstly undergoes an addition process of organolithium reagents to nitriles to generate the imine intermediates in situ. Subsequently, the most challenging step is by employing copper catalytic enantioselective addition of AllylBpin to the imine intermediates to form the final amines in one pot. [ABSTRACT FROM AUTHOR]

The selective synthesis of monomethylated amines with CO2 is particularly challenging because the formation of tertiary amines is thermodynamically more favorable. Herein, a new strategy for the controllable synthesis of N‐monomethylated amines from primary amines and CO2/H2 is explored. First‐principle calculations reveal that the dissociation of H2 via an heterolytic route reduces the reactivity of methylated amines and thus inhibit successive methylation. In situ DRIFTS proves the process of formation and decomposition of ammonium salt by secondary amine reversible binding with H+ on the Ag/Al2O3 catalyst, thereby reducing its reactivity. Meanwhile, the energy barrier for the rate‐determining step of monomethylation was much lower than that of overmethylation (0.34 eV vs. 0.58 eV) means amines monomethylation in preference to successive methylation. Under optimal reaction conditions, a variety of amines were converted to the corresponding monomethylated amines in good to excellent yields, and more than 90 % yield of product was obtained. [ABSTRACT FROM AUTHOR]

Opening the ring of cyclic amines by regioselective fission of one of the carbon–nitrogen bonds greatly expands the repertoire of available nitrogen‐containing skeletons. Unlike approaches starting from cyclic tertiary amines, methods that can directly open secondary amines are still scarce. The present work discloses an efficient reductive ring opening of either of these cyclic amines using PhSiH3 under B(C6F5)3 catalysis. By this, the direct transformation of unstrained cyclic amines into the corresponding acyclic amines is achieved in a simple one‐pot operation. A stepwise mechanism proceeding through the intermediacy of silylammonium ions followed by reductive cleavage of a carbon–nitrogen bond was experimentally verified. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study presents the transformation of olefins to branched amines by combining a hydroformylation/aldol condensation tandem reaction with the reductive amination in a combined multiphase system that can be recycled 9 times. The products are branched amines that are precursors for surfactants. Since the multiphase hydrofomylation/aldol condensation system has already been studied, the first step was to develop the partial hydrogenation of unsaturated aldehydes together with a subsequent reductive amination. The rhodium/phosphine catalyst is immobilized in a polar polyethylene phase which separates from the product phase after the reaction. Reaction and catalyst recycling are demonstrated by the conversion of the C14‐aldehyde 2‐pentylnonenal with the dimethylamine surrogate dimethylammonium dimethylcarbamate to the corresponding tertiary amine with yields up to 88 % and an average rhodium leaching of less than 0.1 % per recycling run. Furthermore, the positive influence of a Bronsted acid and carbon monoxide on the selectivity are discussed. Finally, the two PEG based systems have been merged in one recycling approach, by using the product phase of the hydroformylation aldol condensation reaction for the reductive amination reaction. The yields are stable during a nine recycling runs and the leaching low with 0.09 % over the two recycling stages. [ABSTRACT FROM AUTHOR]

Direct reductive amination (DRA) is a ubiquitous reaction in organic chemistry. This transformation between a carbonyl group and an amine is most often achieved by using a super stoichiometric amount of hazardous hydride reagents, thus being incompatible with many sensitive functional groups. DRA could also be achieved by means of chemo‐ or biocatalysis, thereby attracting the interest of industry as well as academic laboratories due to the virtually perfect atom economy. Although DRAs are well‐established for substrate pairs such as aldehydes with either 1° or 2° amines as well as ketones with 1° amines, the current methodologies are limited in the case of ketones with 2° amines. Herein, we present a general DRA protocol that overcomes this major limitation by means of iridium catalysis. The applicability of the methodology is demonstrated by accessing an unprecedented range of biologically relevant tertiary amines starting from both aliphatic ketones and aliphatic amines. The choice of a disphosphane ligand (Josiphos A or Xantphos) is essential for the success of the transformation. [ABSTRACT FROM AUTHOR]

Intermolecular hydroaminoalkylation reactions of symmetrical and unsymmetrical alkynes with tertiary amines take place in the presence of catalytic amounts of TiBn4, Ph3C[B(C6F5)4], and a sterically demanding aminopyridinato ligand precursor. The resulting products, synthetically and pharmaceutically useful tertiary β,γ‐disubstituted allylic amines, are formed in convincing yields and with excellent stereoselectivity. Particularly promising for future applications is the fact that even the industrial side product trimethylamine can be used as a substrate. [ABSTRACT FROM AUTHOR]

Chiral pseudo[1]rotaxanes and [1]rotaxanes constructed from macrocyclic arenes still remain a big challenge mainly owing to the lack of such chiral macrocycles. In this work, a new system of chiral pseudo[1]rotaxanes formed by self‐inclusion of helic[6]arene containing amide linked with the terminal tertiary amines was first discovered. Based on an atom‐economic stopping strategy, a pair of chiral [1]rotaxanes were conveniently obtained in almost quantitative yields by blocking the pseudo[1]rotaxanes with monobenzyl bromide of tetraphenylethene. The structures of pseudo[1]rotaxanes and [1]rotaxanes were characterized by 2D NMR spectra in solution, combined with DFT calculations. The photophysical properties further revealed the efficient chirality transfer of helic[6]arene to the tetraphenylethene moiety, compared to their unthreaded chiral isomers. The discovery of the chiral pseudo[1]rotaxanes allows for a wide and available synthesis of chiral [1]rotaxanes, and also opening a new avenue to the design of chiral supramolecular materials. [ABSTRACT FROM AUTHOR]

The name of Menshutkin is most frequently associated with his eponymous reaction (the quaternization of tertiary amines with alkyl halides). However, he made encyclopedic contributions to the field of reaction kinetics, where he carried out extensive studies of the effects of reactant structure on the rates of esterification of monohydric, dihydric and trihydric alcohols with monocarboxylic acids, and monobasic and dibasic carboxylic acids and anhydrides with monohydric alcohols. In these studies, he deduced an order of reactivity of alcohols in esterification on the basis of their reactions with acetic acid, and the effects of acid structure on the rates of esterification based on the reaction of the carboxylic acid with isobutyl alcohol. When his attention later turned to the substitution chemistry of amines, he defined the parameters that affected their reactions: anilines were less reactive than alkylamines, secondary more reactive than primary amines, and the reaction was accelerated by replacing benzene as a solvent with alcohols. The wide‐ranging work of Menshutkin, the physical organic chemist, is discussed. [ABSTRACT FROM AUTHOR]

A metal‐free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β‐substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α‐functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β‐cyano esters, α‐aryl alkylnitriles, and TBS‐protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine). [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light‐mediated therapies. Since long‐wavelength photoluminescence typically involves extensive π‐conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3‐cyanoformazans affords efficient production of relatively simple NIR‐active BF2 formazanate dyes (λabs=691–760 nm, λPL=834–904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF2 formazanate moieties. Density‐functional calculations indicate that the NIR electronic transitions in BF2 formazanates are of π→π*‐type, but do not always involve strong charge transfer. [ABSTRACT FROM AUTHOR]

We propose post‐metalation modification as a useful strategy to control the guest recognition behavior of a metal‐containing macrocyclic host. This is based on the ligand exchange of the axial ligands of a cobalt(III) dinuclear macrocyclic host, [LCo2X4]2+ (X=axial amine ligand). Four piperidine ligands in [LCo2(pip)4]2+ (pip=piperidine) were site‐selectively replaced with primary amines. The competitive experiments revealed that the order of the affinity toward the cobalt centers in [LCo2X4]2+ is primary amine > secondary amine > tertiary amine and that the piperidine‐coordinating complex, [LCo2(pip)4]2+, was reasonably reactive among the isolable complexes. Indeed, two piperidine ligands at the diagonal positions in [LCo2(pip)4]2+ were site‐selectively replaced with pyridine or acetate ion. The replacement of piperidine with acetate ion significantly enhanced the recognition ability towards Na+. [ABSTRACT FROM AUTHOR]

Mechanistic studies with 5‐ethyl‐3‐methyllumiflavinium (Fl+) perchlorate, a biomimetic model for flavoenzyme monoamine oxidase B (MAO‐B) catalysis, and the tertiary, allyl amine 1‐methyl‐4‐(1‐methyl‐1 H‐pyrrol‐2‐yl)‐1,2,3,6‐tetrahydropyridine (MMTP) reveal that proton‐coupled electron transfer (PCET) may be an important pathway for MAO catalysis. The first step involves a single‐electron transfer (SET) leading to the free radicals Fl. and MMTP. the latter produced by deprotonation of the initially formed and highly acidic MMTP.+. Molecular oxygen (O2) is found to play a hitherto unrecognized role in the early steps of the oxidation. MMTP and several structurally similar tertiary amines are the only tertiary amines oxidized by MAO, and their structural/electronic properties provide the key to understanding this behavior. A general hypothesis about the role of SET in MAO catalysis, and the recognition that PCET occurs with appropriately substituted substrates is presented. [ABSTRACT FROM AUTHOR]

Water‐soluble donor–acceptor‐type fluorophore 15Nap‐Cl having two trifluoromethyl groups and a Cl group on a 1,5‐aminonaphthyridine framework was prepared. Fluorophore 15Nap‐Cl showed strong solvatochromic fluorescence, and, as the solvent polarity increased, a bathochromic shift was observed accompanied by an increase in the fluorescence quantum yield. In addition, in the presence of amines such as ethylamine, diethylamine, and aniline, further considerable bathochromic shifts in the fluorescence were observed. Density functional calculations identified the source of the fluorescence behavior as exciplex formation between 15‐Nap‐Cl and the corresponding amine. The fluorescence behavior was exploited to fabricate a sensor that can identify various primary, secondary, and tertiary amines. [ABSTRACT FROM AUTHOR]

In this study, the unique capacity of bifunctional Brønsted bases to generate α‐branched ketone dienolates and control both site‐ and stereoselectivity of their addition reactions to representative classes of carbon electrophiles (i.e. vinyl sulfones, nitroolefins, formaldehyde) is documented. We demonstrate that by using selected chiral tertiary amine/squaramide catalysts, the reactions of β,γ‐unsaturated cycloalkanones proceed through the dienolate Cα almost exclusively and provide all‐carbon quaternary cyclic ketone adducts in good yields with very high enantioselectivities. A minor amount (<5 %) of γ‐addition is observed when nitroolefins are used as electrophiles. The parent acyclic ketone dienolates proved to be less reactive under these conditions, and thus still constitute a challenging class of substrates. Quantum chemical calculations correctly predict these differences in reactivity and explain the observed site‐specificity and enantioselectivity. [ABSTRACT FROM AUTHOR]

Manganese(III) porphyrin chloride complexes have been developed for the first time as catalysts for the acceptorless dehydrogenative coupling of alcohols and amines. The reaction has been applied to the direct synthesis of imines, tertiary amines and quinolines where only hydrogen gas and/or water are formed as the by‐product(s). The mechanism is believed to involve the formation of a manganese(III) alkoxide complex which degrades into the aldehyde and a manganese(III) hydride species. The latter reacts with the alcohol to form hydrogen gas and thereby regenerates the alkoxide complex. [ABSTRACT FROM AUTHOR]

A new strategy has been established for the synthesis of polysubstituted morpholin‐2‐ones through Stevens rearrangements of tertiary amines via in situ activation with epoxides. A range of α‐amino acid‐derived tertiary allylic, propargylic, and benzylic amines reacted with epoxides in the presence of zinc halide catalysts to afford structurally diverse allyl‐, allenyl‐, and benzyl‐substituted morpholin‐2‐ones, respectively, in moderate‐to‐good yields with high regioselectivity. The process involves [2,3]‐ and [1,2]‐Stevens rearrangements of quaternary ammonium ylide intermediates and constitutes a very convenient method to prepare polysubstituted morpholin‐2‐ones through tandem formation of C−N, C−O, and C−C bonds. Moreover, replacing epoxides with aziridines permitted the synthesis of polysubstituted piperazin‐2‐ones. New Stevens rearrangement: Zinc‐halide‐catalyzed ring‐opening of epoxides with α‐amino acid‐derived tertiary allylic, propargylic, and benzylic amines followed by [2,3]‐ and [1,2]‐Stevens rearrangements of the resulting quaternary ammonium ylide intermediates has been established as a convenient method to access polysubstituted morpholin‐2‐ones through tandem formation of C−N, C−O, and C−C bonds (see scheme). [ABSTRACT FROM AUTHOR]

Various sets of enolizable alkynyl ketones (including methyl ynones with α‐aryl, α‐alkenyl, and α‐alkoxy groups) were able to react smoothly with nitroolefins with the assistance of bifunctional Brønsted base/H‐bond catalysts to provide adducts with two consecutive tertiary stereocenters in a highly diastereo‐ and enantioselective fashion. Further transformation of the obtained adducts into optically active acyclic and polycyclic molecules, including some with intricate carbon skeletons, was also demonstrated. Donor ynones: under very mild conditions linear ynones with no additional electron‐withdrawing group at Cα get activated by tertiary amine/squaramide chiral catalysts and react with nitroolefins in a highly diastereo‐ and enantioselective fashion. In this way, an easy access to branched alkyl alkynyl ketones with two contiguous stereocenters and derivatives thereof is provided. [ABSTRACT FROM AUTHOR]

Air and visible light have been used in facile direct C−H oxidation of cyclic tertiary amines at ambient conditions, employing organic dyes as photocatalysts and LED. Tolerance of this new environmentally compatible protocol to various side‐chain derivatizations of tryptoline and tetrahydroisoquinoline substrates was demonstrated. The developed method provides a straightforward and sustainable route towards δ‐lactams, which feature strong antiviral properties (EC50 down to 4.6±1.8 μm) against human cytomegalovirus (HCMV). The clear advantages, which are easily available and inexpensive reagents, organic dyes, visible light, air/O2 and atom efficiency, make this system highly appealing for synthesis of versatile Strychnocarpine alkaloid derivatives with antiviral activity. Light as air: Visible light and air were used as easily available and inexpensive reagents for direct metal‐free C−H photooxidation of cyclic tertiary amines towards new antiviral δ‐lactams at ambient conditions. This facile and atom‐efficient method is highly appealing for synthesis of versatile Strychnocarpine alkaloid derivatives (see scheme). [ABSTRACT FROM AUTHOR]

N‐Heterocycles have been found in a large number of natural products, drug molecules, and bioactive compounds, and they thereby play a vital role in diverse research disciplines including drug discovery, organic synthesis, chemical biology, and material science. To this end, the development of new methods and strategies for the construction of N‐heterocyclic frameworks is arguably one of the most dynamic and significant research areas in organic synthesis. One of these powerful approaches to the synthesis of N‐heterocycles is to establish cyclization reactions based on the transformation of tertiary amines, which has emerged as an attractive research topic. In this Minireview, the significant achievements in the construction of N‐heterocycles through cyclization of tertiary amines are highlighted and a comprehensive overview of the rational design, development, and application of these synthetic methods is presented. Going in circles: N‐Heterocycles play an important role in many research areas such as organic synthesis, drug discovery, chemical biology, and material science. This Minireview highlights the significant achievements in constructing N‐heterocycles through cyclization of tertiary amines and elucidates the principles and logic in the discovery of these reactions. [ABSTRACT FROM AUTHOR]

Abstract: A CoII/Box‐catalyzed [Box=bis(oxazoline)] enantioselective addition of potassium allyltrifluoroborate to cyclic ketimines was developed, providing the corresponding chiral α‐tertiary amines in high yields and with good enantioselectivity values. Alkoxycarbonyl‐ and alkyl‐substituted saccharin‐derived ketimines are suitable substrates for this allylation reaction. The product can be converted to complex molecules over several simple steps, including a precursor of MK‐0371, which is a kinesin spindle protein inhibitor. In addition, this catalytic system showed a strong positive nonlinear effect. [ABSTRACT FROM AUTHOR]

A divergent synthesis of optically active quaternary Δ4- and Δ5-dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α-substituted isocyano(thio)acetates to vinyl ketones that is general for both α-aryl and α-alkyl isocyano(thio)acetates. The new tetrasubstituted C−N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H⋅⋅⋅H interatomic distance in the solid state. [ABSTRACT FROM AUTHOR]

Transition-metal-catalyzed electrophilic amination has been developed into a powerful tool for C−N bond construction. So far, O-benzoylhydroxylamines are the most widely used electrophilic aminating reagents. Herein, we summarize the recent advances of O-benzoylhydroxylamines involved in electrophilic amination catalyzed by transition metals. Several pioneering studies and some of the relevant mechanisms are discussed in this review. [ABSTRACT FROM AUTHOR]

A visible-light-mediated [3+3] annulation of tertiary amines with α-trifluoromethyl alkenes was developed. The reaction offers a direct route to fluorinated tetrahydropyridines and azabicyclo[3.m.1] frameworks under very mild conditions. This protocol presents a rare example of dual sp3 C−H functionalization of tertiary amines with the formation of two different C−C bonds (one sp3-sp3 bond, one sp2-sp3 bond). Moreover, two consecutive C−F substitutions in a trifluoromethyl group were achieved in one pot using visible light photoredox catalysis, which enables an unprecedented ring construction. [ABSTRACT FROM AUTHOR]

The streamlined catalytic access to enantiopure allylic amines as valuable precursors towards chiral β- and γ-aminoalcohols as well as α- and β-aminoacids is desirable for industrial purposes. In this article an enantioselective method is described that transforms achiral allylic alcohols and N-tosylisocyanate in a single step into highly enantioenriched N-tosyl protected allylic amines via an allylic carbamate intermediate. The latter is likely to undergo a cyclisation-induced [3,3]-rearrangement catalysed by a planar chiral pentaphenylferrocene palladacycle in cooperation with a tertiary amine base. The otherwise often indispensable activation of palladacycle catalysts by a silver salt is not required in the present case and there is also no need for an inert gas atmosphere. To further improve the synthetic value, the rearrangement was used to form dimethylaminosulfonyl-protected allylic amines, which can be deprotected under non-reductive conditions. [ABSTRACT FROM AUTHOR]

Enantioselective formal hetero-Diels-Alder reactions of trifluoromethylated enones and 2-amino-1,3-butadienes generated in situ from aliphatic acyclic enones and chiral primary amines are reported. The corresponding tetrahydropyran-4-ones are formed in up to 94 % yield and with up to 94 % ee. The reaction was carried out through a stepwise mechanism, including initial aminocatalytic aldol condensation of 2-amino-1,3-butadiene to the trifluoromethylated carbonyl group followed by an intramolecular oxa-Michael addition. Both NMR investigation and theoretical calculations on the transition state indicate that the protonated tertiary amine could effectively activate the carbonyl group of the trifluoromethyl ketone to promote the addition process through hydrogen-bonding interaction of NH⋅⋅⋅F and NH⋅⋅⋅O simultaneously, and thus provide a chiral environment for the approach of amino-1,3-butadienes to the activated trifluoromethyl ketone, resulting in high enantioselectivity. [ABSTRACT FROM AUTHOR]

The synthesis, photophysical and electrochemical properties as well as theoretical calculation studies of a newly designed triphenylamine derivative are described. This original compound displays one neutral form, three oxidized forms, and two protonated forms with distinct photophysical characteristics. The interplay of the emission with the protonation or the redox state (electrofluorochromism) has been explored and an on-off-on-off fluorescence switching was observed in the case of oxidation and an on-on-off fluorescence switching in the case of protonation. [ABSTRACT FROM AUTHOR]

Amines, hydrogenation, iridium, ketones, reductive amination, high-throughput experimentation Keywords: amines; high-throughput experimentation; hydrogenation; iridium; ketones; reductive amination EN amines high-throughput experimentation hydrogenation iridium ketones reductive amination 1 1 1 06/29/22 20220627 NES 220627 B An iridium-catalyzed methodology b leads to fully aliphatic tertiary amines starting from readily available ketones and amines. Front Cover: Iridium-Catalyzed Direct Reductive Amination of Ketones and Secondary Amines: Breaking the Aliphatic Wall (Chem. Eur. J. 36/2022). [Extracted from the article]

A novel palladium-catalyzed norbornene-mediated three-component reaction for the construction of ortho-alkenyl aromatic tertiary amines has been achieved, which represents a useful extension of the Catellani-type tandem ortho-selective CH amination transformations. [ABSTRACT FROM AUTHOR]

A cheap, mild and environmentally friendly oxidation of tertiary amines and azines to the corresponding N-oxides is reported by using polyfluoroalkyl ketones as efficient organocatalysts. 2,2,2-Trifluoroacetophenone was identified as the optimum catalyst for the oxidation of aliphatic tertiary amines and azines. This oxidation is chemoselective and proceeds in high-to-quantitative yields utilizing 10 mol % of the catalyst and H2O2 as the oxidant. [ABSTRACT FROM AUTHOR]

CycloN2P2‐Phos! The use of the multidentate phosphine, CycloN2P2‐Phos (see graphic), which contains four heteroatoms (two nitrogen and two phosphorus atoms), in the palladium‐catalyzed asymmetric allylic etherification (AAE) of alcohols and silanols leads to excellent levels of enantioselectivity (up to 99 % ee). [ABSTRACT FROM AUTHOR]

Herein, a promising sensing approach based on the structure fragmentation of poly(amidoamine) (PAMAM) dendrimers for the selective detection of intracellular hypochlorite (OCl−) is reported. PAMAM dendrimers were easily disrupted by a cascade of oxidations in the tertiary amines of the dendritic core to produce an unsaturated hydroxylamine with blue fluorescence. Specially, the novel fluorophore was only sensitive to OCl−, one of reactive oxygen species (ROS), resulting in an irreversible fluorescence turn-off. The fluorescent hydroxylamine was selectively oxidised by OCl− to form a labile oxoammonium cation that underwent further degradation. Without using any troublesomely synthetic steps, the novel sensing platform based on the fragmentation of PAMAM dendrimers, can be applied to detect OCl− in macrophage cells. The results suggest that the sensing approach may be useful for the detection of intracellular OCl− with minimal interference from biological matrixes. [ABSTRACT FROM AUTHOR]

Donor-acceptor (D-π-A) systems that combine triarylamine donor blocks and dicyanovinyl (DCV) acceptor groups have been synthesized. Starting from the triphenylamine (TPA)thiopheneDCV compound ( 1) as a reference system, various synthetic approaches have been developed for controlling the light-harvesting properties and energy levels of the frontier orbitals in this molecule. Thus, the introduction of methoxy groups onto TPA, the replacement of one phenyl ring of TPA by a thiophene ring, or the extension of the π-conjugating spacer group lead to the modulation of the HOMO level. On the other hand, the fusion of the DCV group onto the vicinal thiophene ring by an ortho-phenylene bridge allows for a specific fine-tuning of the LUMO level. The electronic properties of the molecules were analyzed by using UV/Vis spectroscopy and cyclic voltammetry and the compounds were evaluated as donor materials in basic bilayer planar heterojunction solar cells by using C60 as acceptor material. The relationships between the electronic properties of the donors and the performance of the corresponding photovoltaic devices are discussed. Bilayer planar heterojunction solar cells that used reference compound 1 and C70 afforded power-conversion efficiencies of up to 3.7 %. [ABSTRACT FROM AUTHOR]

Amines, molecular structures, quantum chemistry, steric hindrance, X-ray diffraction Keywords: amines; molecular structures; quantum chemistry; steric hindrance; X-ray diffraction EN amines molecular structures quantum chemistry steric hindrance X-ray diffraction 3571 3571 1 02/24/21 20210219 NES 210219 B Even record-breaking steric stress b cannot enforce complete planarization of the nitrogen atom in trialkylamines. Moreover, quantum chemical calculations generate the precise gas-phase structures of the sterically overcrowded tertiary amines showing heights of the NC3 pyramids and preferred molecular conformers, which are similar to those resulting from the X-ray analysis. [Extracted from the article]

Electrophilic Amination The task of realizing selective assembly of amines from readily available precursors has become a prominent objective in organic chemistry. The importance of C−N bond construction by application of O‐benzoylhydroxylamines in transition‐metal‐catalyzed electrophilic amination has led to the rapid development of this field. In their Review article on page 2481 ff., Q. Liu, H. Liu and colleagues describe the recent advances of O‐benzoylhydroxylamines involved in electrophilic amination catalyzed by transition metals. Several pioneering studies and some of the relevant mechanisms are discussed. [ABSTRACT FROM AUTHOR]