Primary Aryl Research Articles

Liquid–Liquid Equilibria in Aqueous Mixtures of Phosphoric Acid with Two Primary Aryl Alcohols at T = (298.2, 308.2, and 318.2) K: Measurements and Correlation

This comparative study reports the measured liquid–liquid equilibrium (LLE) data and phase diagrams for the two ternary systems of {water + phosphoric acid + aryl alcohols (2-phenylethanol and 3-phenylpropanol)} at temperatures of (298.2, 308.2, and 318.2) K and atmospheric pressure (p = 0.1 MPa). Solubility data and mutual solubilities between the aryl alcohols and water were determined using turbidity measurements (cloud point titration method). Tie-line data were measured through acid–base titration and refractive index measurements. The results were validated through the Karl-Fischer titration method and mass balance calculations. The studied systems displayed Treybal's type-1 phase behavior, having one liquid pair that is partially miscible. The Othmer–Tobias correlation equation was applied to check the reliability of the tie lines. The experimental LLE data were correlated using the NRTL and UNIQUAC thermodynamic models, and the model binary interaction parameters between each pair of components were calculated. The results show the ability of these correlation models in representing the LLE data with acceptable average root-mean-square deviation (rmsd) values. As a result, the effect of temperature on the immiscibility region for the studied systems is small. For the studied systems, the separation factors are larger than unity, which means that the aryl alcohols have potential for separation of phosphoric acid from water.

Introduction of Two New Brønsted Acidic Ionic Liquids for the Formamide and Formamidine Derivatization of Amines

AbstractIn this study, two recently reported 1,4‐diazabicyclo[2.2.2]octane (DABCO)‐based ionic liquids were used for the acceleration of the N‐formylation of primary and secondary amines with formic acid under solvent‐free conditions. These reagents have also been used for the efficient synthesis of N, N′‐diaryl formamidines through reaction of triethyl orthoformate with primary aryl amines. These methods offer several advantages such as excellent yields, short reaction times and simple work‐up with the environmentally friendly procedure.

One‐Pot Generation of Benzynes from Phenols: Formation of Primary Anilines by the Deoxyamination of Phenols

Benzynes were selectively generated in-situ from phenols and trapped regioselectively by potassium hexamethyldisilazide to form primary anilines following acidic workup. The direct conversion of a phenolic hydroxyl group to a free amino group is a useful method for the preparation of primary aryl amines that are hard to synthesize using coupling reactions involving phenol derivatives with ammonia. While reactions of ortho - and meta -substituted phenols produced meta-substituted anilines exclusively, those of para -substituted phenols provided ortho -silylanilines.

A new ligand for copper-catalyzed amination of aryl halides to primary(hetero)aryl amines

N,N′-Bis(3,5-dimethoxyphenyl)cyclopentane-1,1-dicarboxamide was found as a new ligand for copper-catalyzed amination of aryl iodides, bromides and chlorides to afford various primary (hetero)aryl amines. These reactions proceeded efficiently under mild conditions when inexpensive aqueous ammonia (28% NH3 in H2O) was used as the amino source.

Transition-Metal-Free Decarboxylative Amidation of Aryl α-Keto Acids with Diphenylphosphoryl Azide: New Avenue for the Preparation of Primary Aryl Amides

Transition-Metal-Free Decarboxylative Amidation of Aryl <i>α</i>-Keto Acids with Diphenylphosphoryl Azide: New Avenue for the Preparation of Primary Aryl Amides

Reversible dehydrogenation of a primary aryl borane.

The consecutive activation of B-H bonds in mesitylborane (H2BMes; Mes = 2,4,6-(CH3)3C6H2) by a 16-electron rhodium(i) monocarbonyl complex, (iPrNNN)Rh(CO) (1-CO; iPrNNN = 2,5-[iPr2P[double bond, length as m-dash]N(4-iPrC6H4)]2N(C4H2)-) is described. Dehydrogenative extrusion of the {BMes} fragment led to the isolation of (iPrNNN)(CO)RhBMes (1-BMes). Addition of H2 gas to 1-BMes regenerated 1-CO and H2BMes, highlighting the ability of 1-CO to facilitate interconversion of {BMes} with dihydrogen. Reactivity studies revealed that 1-BMes promotes formal group transfer and that {BAr} fragments accessed by dehydrogenation are reactive entities.

Anticancer activities of vitamin K3 analogues.

In a previous study we reported on the synthesis of 1,4-naphthoquinone-sulfides by thiolation of 1,4-naphthohydroquinones with primary aryl and alkyl thiols using laccase as catalyst. These compounds were synthesized as Vitamin K3 analogues. Vitamin K3 (VK3; 2-methyl-1,4-naphthoquinone; menadione) is known to have potent anticancer activity. This investigation reports on the anticancer activity of these VK3 analogues against TK10 renal, UACC62 melanoma, MCF7 breast, HeLa cervical, PC3 prostate and HepG2 liver cancer cell lines to evaluate their cytostatic effects. A 1,4-naphthohydroquinone derivative exhibited potent cytostatic effects (GI50 = 1.66-6.75μM) which were better than that of etoposide and parthenolide against several of the cancer cell lines. This compound produces reactive oxygen species and disrupts the mitochondrial membrane potential in the MCF7 breast cancer cell line which is an indication that the cells undergo apoptosis. The 1,4-naphthoquinone sulfides also had potent cytostatic effects (GI50 = 2.82-9.79μM) which were also better than that of etoposide, parthenolide and VK3 against several of the cancer cell lines. These compounds are generally more selective for cancer cells than for normal human lung fetal fibroblasts (WI-38). They also have moderate to weak cytostatic effects compared to etoposide, parthenolide and VK3 which have potent cytostatic effects against WI-38. One analogue induces apoptosis by activating caspases without arresting the cell cycle in the MCF7 breast cancer cell line. These results inspire further research for possible application in cancer chemotherapy.

Mechanistic Study of Hydroamination of Alkyne through Tantalum-Based Silica-Supported Surface Species

Selective hydroamination of terminal alkynes with primary aryl amines is catalyzed by an unprecedented well-defined silica-supported tantalum complex [(≡Si–O−)Ta(η1σ-NEtMe)2(=NtBu)]. A molecular-level characterization of the surface organometallic Ta species was done with the help of characterization techniques including in situ infrared, 1H and 13C solid-state NMR (including double and triple quanta sequencing), and X-ray absorption spectroscopies. These were complemented by the state-of-the-art DNP-SENS 15N characterization. Several catalytic intermediates have been isolated, in particular the 4-membered metallacycle ring intermediate resulting from the anti-Markovnikov addition of the alkyne to the surface tantalum imido. A mechanism is proposed that is on the isolation of all intermediates. A density functional theory (DFT) calculation has confirmed all the elementary steps and intermediates that were fully characterized.

Copper(II) complexes with barbiturate derivatives: Synthesis, characterization and catalytic applications

Barbiturate derivatives were prepared by the reaction of 5-formylbarbiturates and primary aryl amines. The corresponding copper(II) complexes were synthesized by treatment of copper(II) acetate monohydrate with the prepared barbiturate derivatives. All the novel compounds were characterized by elemental analysis and spectroscopic methods. The structures of 3b and 3j were determined with X-ray crystallography. The X-ray crystallographic studies revealed that complexes 3b and 3j are 2-D coordination polymers. Also, the catalytic activities of the copper(II) complexes were examined for the peroxidative oxidation of cyclohexane under mild conditions. The results showed that the yields of the oxidation products were in the range 11.3–22.1%, depending upon the complex used and the promoter.

The mechanism and structure-activity relationship of amide bond formation by silane derivatives: a computational study.

The condensation of carboxylic acids and amines mediated by silane derivatives provided a straightforward and sustainable method for amide bond formation with minimal waste. However, the detailed mechanism and structure-activity relationship of substrates, the topics that are of interest for both academic and industrial applications, were not clear. Herein, a systematic computational study was conducted to solve the two questions. We found that the two previously proposed mechanisms involving intramolecular acyl transfer or silanolate were less likely because the associated silanone intermediate and zwitterion adducts were too unstable with higher overall energy barriers. By comparison, the mechanism involving deprotonation of carboxylic acids, addition of carboxylates on silane reagents, dihydrogen formation to afford an acyloxysilane intermediate, carboxylic-acid-assisted addition of amines, and concerted proton transfer/amide formation, was found to be more favorable with overall energy barriers varying between 24 and 28 kcal mol-1 for the different calculated cases. Meanwhile, the dihydrogen formation and amide formation processes are both potential rate-determining steps. Energy composition, atomic charge, and distortion-interaction analyses indicated that the steric effect of silane reagents was more important than the electronic effect, making less bulky silane reagents more reactive. On the other hand, the dihydrogen formation process was mainly controlled by the electronic effect of the substituents of carboxylic acids and amines while the amide formation process was mainly influenced by their steric effect. As a result, less bulky, less acidic alkyl carboxylic acids are more reactive than unsaturated carboxylic acids, and less bulky, medium basic primary alkyl amines are more reactive than secondary alkyl amines and primary aryl amines. The related results provided deeper mechanistic insights into the amide bond formation mediated by silane derivatives and can act as a reference for further experimental design.

Reactions of Low-Coordinate Cobalt(0)-N-Heterocyclic Carbene Complexes with Primary Aryl Phosphines.

Aiming to get knowledge on the reactivity of low-coordinate cobalt(0) species toward primary phosphines, the reactions of [(IPr)Co(vtms)2] and [(ICy)2Co(vtms)] (IPr = 1,3-bis(2',6'-diisopropylphenyl)imidazol-2-ylidene, ICy = 1,3-dicyclohexylimidazol-2-ylidene, and vtms = vinyltrimethylsilane) with several primary aryl phosphines have been examined. The reactions of [(IPr)Co(vtms)2] and [(ICy)2Co(vtms)] with H2PDmp (Dmp = 2,6-dimesitylphenyl) at 80 °C furnish the diamagnetic cobalt(I) phosphido complexes [(NHC)Co(PHDmp)] (NHC = IPr, 1; ICy, 2) that feature the Co-(η6-mesityl) interaction. Complex 1 can coordinate CO to generate the terminal phosphido complex [(IPr)Co(CO)3(PHDmp)] (3) and can be oxidized by [Cp2Fe][BArF4] to yield the cobalt(II) phosphido complex [(IPr)Co(PHDmp)][BArF4] (4, BArF4 = tetrakis(3,5-di(trifluoromethyl)phenyl)borate). For the reactions with sterically less-hindered primary phosphines, [(IPr)Co(vtms)2] is inert toward H2PC6H2-2,4,6-Me3 (H2PMes) at room temperature, whereas [(ICy)2Co(vtms)] can react with H2PMes at room temperature to produce the cobalt(II) phosphido alkyl complex trans-[(ICy)2Co(CH2CH2SiMe3)(PHMes)] (5). At 80 °C, the cobalt(0) alkene complexes [(IPr)Co(vtms)2] and [(ICy)2Co(vtms)] and also the cobalt phosphido complexes, 1, 2, and 5 can serve as precatalysts for the dehydrocoupling reaction of H2PMes to afford MesHPPHMes. NHC-Co(I)-phosphido species are proposed as the in-cycle intermediates for these cobalt-catalyzed dehydrocoupling reactions.

Synthesis of Symmetrical N-Aryl-C-phosphonoacetamidines

An efficient synthesis of a series of novel symmetrical N-aryl-C-phosphonoacetamidines through reaction of diisopropyl (chloroethynyl)phosphonate with primary aryl amines was developed. This procedure tolerates a wide range of functional groups and has a good atom economy. The (E)-isomer was the major product that crystallized preferentially over the (Z)-isomer.

P,N]-phosphinobenzimidazole ligands in palladium-catalyzed C-N cross-coupling reactions: The effect of the N-substituent of the benzimidazole scaffold on catalyst performance

A series of [P,N]-phosphinobenzimidazole ligands is reported in which the charge (anionic vs. neutral) and size of the N-substituent of the benzimidazole scaffold has been varied. In order to evaluate the impact of the substituent's properties on the performance of the metal in catalytic reactions, each ligand was screened for its ability to promote the cross-coupling of aryl bromides with various primary aryl amines using palladium as the metal source. In general, the ligands formed active cross-coupling catalysts with palladium. Moreover, the ligand variants containing larger N-substituents boosted the efficiency of the cross-coupling reaction considerably, while their charge (either anionic or neutral) appeared to have no significant impact.

Recyclable Polymer-Supported Terpyridine–Palladium Complex for the Tandem Aminocarbonylation of Aryl Iodides to Primary Amides in Water Using NaN3 as Ammonia Equivalent

Primary aromatic amides are valuable compounds, which are generally prepared via Beckmann rearrangement of oximes and the hydration of nitriles in organic solvents. We investigated the environmentally friendly catalytic aminocarbonylation in water. Thus, a novel heterogeneous transition-metal catalyst, a polymer-supported terpyridine–palladium(II) complex, was prepared and found to promote azidocarbonylation of aryl iodides with NaN3 and to reduce the generated benzoyl azides in water under CO gas to yield primary aryl amides with high to excellent yield in a one-pot reaction. The catalyst was recovered and reused several times with no loss of catalytic activity.

Green synthesis and evaluation of 5-(4-aminophenyl)-4-aryl-4H-1, 2, 4-triazole-3-thiol derivatives

The green synthesis of 5-(4-aminophenyl)-4-aryl-4H-1,2,4-triazole-3-thiol was achieved in four steps, In first step, 4-amino benzoic acid refluxed in ethanol along with catalyst Conc. Sulphuric acid to produce ethyl-4-amino benzoate I. Further compound I refluxed with hydrazine hydrate in ethanol to produce 4-amino benzohydrazide II. Compound II refluxed in ethanolic potassium hydroxide with carbon disulfide to produce 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol III. Compound III refluxed in ethanol with different substituted primary aryl amine gave title compounds 5-(4-aminophenyl)-4-aryl-4H-1,2,4-triazole-3-thiol IVa-o. The compounds obtained were identified by FT-IR, 1H-NMR, GC- mass spectroscopy data, and elemental analysis and also screened for in-vivo antimicrobial activity. In vitro antibacterial activity was carried out against organisms like E.coli. K.pneumonia, S.aureus, and B.subtilis as well as in vitro antifungal activity were carried out against organisms like A.niger and S.cerevisiae. In vitro antimicrobial evaluation, the most potent broad spectrum compound IVc, IVd and IVf were found significant agent against standard drug Norfloxacin and Ketoconazole.

High yielding electrophilic amination method for arylcopper reagents

ABSTRACTThe facilitative effect of some P-, N-, S-, and O-donor ligands in the reaction of arylcoppers with acetone O-(mesitylenesulfonyl)oxime was examined to develop a synthesis method for functionalized primary aryl amines under mild reaction conditions. Our research showed that electrophilic amination of monoaryl coppers with ketoximes can be facilitated using appropriate ligand to supply significant increase in the yield. Also, we have seen that this ligand-facilitated method is applicable in terms of arylcopper and ketoxime type and allows synthesis of primary aryl amines in good to high yields easily at room temperature in very short reaction time.

Nickel-Catalyzed Synthesis of Primary Aryl and Heteroaryl Amines via C–O Bond Cleavage

A nickel-catalyzed protocol for the conversion of aryl and heteroaryl alcohol derivatives to primary and secondary aromatic amines via C(sp2)-O bond cleavage is described. The new amination protocol can be applied to a range of substrates bearing diverse functional groups and uses readily available benzophenone imines as an effective nitrogen source.

Cu(Ⅱ)-promoted oxidative C-N bond cleavage of N-benzoylamino acids to primary aryl amides

Cu(Ⅱ)-promoted oxidative C-N bond cleavage of N-benzoylamino acids to primary aryl amides

Highly Chemoselective Iridium Photoredox and Nickel Catalysis for the Cross-Coupling of Primary Aryl Amines with Aryl Halides.

A visible-light-promoted iridium photoredox and nickel dual-catalyzed cross-coupling procedure for the formation C-N bonds has been developed. With this method, various aryl amines were chemoselectively cross-coupled with electronically and sterically diverse aryl iodides and bromides to forge the corresponding C-N bonds, which are of high interest to the pharmaceutical industries. Aryl iodides were found to be a more efficient electrophilic coupling partner. The coupling reactions were carried out at room temperature without the rigorous exclusion of molecular oxygen, thus making this newly developed Ir-photoredox/Ni dual-catalyzed procedure very mild and operationally simple.

Highly Chemoselective Iridium Photoredox and Nickel Catalysis for the Cross‐Coupling of Primary Aryl Amines with Aryl Halides

AbstractA visible‐light‐promoted iridium photoredox and nickel dual‐catalyzed cross‐coupling procedure for the formation C−N bonds has been developed. With this method, various aryl amines were chemoselectively cross‐coupled with electronically and sterically diverse aryl iodides and bromides to forge the corresponding C−N bonds, which are of high interest to the pharmaceutical industries. Aryl iodides were found to be a more efficient electrophilic coupling partner. The coupling reactions were carried out at room temperature without the rigorous exclusion of molecular oxygen, thus making this newly developed Ir‐photoredox/Ni dual‐catalyzed procedure very mild and operationally simple.