Products 3a Research Articles

New Cu (I) complexes as catalyst for “click” reaction: An experimental and computational study

In this work, two novel well‐defined Cu (I) complexes of a Schiff base ligand are described. For this purpose, N, N′‐bis (trans‐cinnamaldehyde) ethylenediimine [C20H20N2] (L) and Cu (I) complex of the type [CuC20H20N2)PPh3Cl] (C1) and [Cu(C20H20N2)PPh3Br] (C2) were synthesised. IR, NMR, XRD and TGA analyses were used to characterise these compounds and single‐crystal X‐ray crystallography confirmed the structure of the compounds. The catalytic activity of the synthesised complexes was studied in azide‐alkyne click reaction (AAC) and the best reaction condition was 15 mol% catalyst, 30 min and 45°C in water, which can be considered moderate catalytic activity for the complexes. Material Studio 2017 software was used to obtain the geometry, energy, HOMO and LUMO of all structures by the quantum calculations (module DMol3 and LDA/PWC). The computational results showed catalyst C2 has more reactivity than catalyst C1, and the C1‐catalysed products form faster than the C2‐catalysed products exceptions 4a and 4b. Product 4b (resulting catalyst C2) is formed faster than product (4a).

A New Approach to the Synthesis of Nanocrystalline Cobalt Boride in the Course of the Thermal Decomposition of Cobalt Complexes [Co(DMF)6]2+ with Boron Cluster Anions

In the course of the study, nanocrystalline cobalt monoboride was prepared by thermal decomposition of precursors [Co(DMF)6][An], where [An] = [B12H12]2- (1), [trans-B20H18]2- (2) or [B10Cl10]2- (3) in an argon atmosphere. Three new salt-like compounds 1-3 were prepared when Co(NO3)2 was allowed to react with (Et3NH)2[An]. Compound 1 is new; the structures of compounds 2 and 3 have been previously reported. Samples 1-3 were annealed at 900 °C in argon to form samples 1a-3a, which were characterized by single crystal XRD for 1 and powder XRD for 1-3. Powder XRD on the products showed the formation of BN and CoB for 1a in a 1:1 ratio; 2a gave a higher CoB:BN ratio but an overall decreased crystallinity. For 3a, only CoB was found. IR spectra of samples 1a-3a as well as X-ray spectral fluorescence analysis for 3a confirmed these results. The nanoparticular character of the decomposition products 1a-3a was shown using TEM; quite small particle sizes of about 10-15 nm and a quite normal size distribution were found for 1a and 2a, while the decomposition of 3 gave large particles with 200-350 nm and a broad distribution.

DFT study on stereoselective Rh-catalyzed intramolecular [2 + 2 + 2] cycloaddition of allene–ene–ynes

CAT catalyzes the reaction of 1a to generate intermediate INT2, which is a common intermediate to generate final products 2a and 3a.

Modulation of magnetization dynamics of an Er(III) coordination polymer by the conversion of a ligand to a radical using UV light.

Light-induced substance conversion is highly promising for creating new radical-based compounds. Herein, we report an Er(III) coordination polymer [Er(CA)(ACA)(DMF)(H2O)]n (1) and its Y(III)-diluted analogue 1@Y (H2CA = 2,5-dichloro-3,6-dihydroxy-p-quinone, HACA = 9-anthracene carboxylic acid) with the light-induced transformation of the ligand to a radical. The χMT values of light-transformed products 1a and 1a@Y are higher than those of 1 and 1@Y, respectively, due to the formation of radicals by ultraviolet light irradiation, confirmed by EPR measurement as well. The effective energy barriers for magnetization reversal (Ueff) decrease from 72 K for 1 to 67 K for 1a, and from 117 K for 1@Y to 94 K for 1a@Y. This work not only provides a new light-conversion system but also reveals the nature of photo-induced variation of magnetic properties.

Chiral Lewis Acid-Catalyzed Norrish Type II Cyclization to Synthesize α-Oxazolidinones via Enantioselective Protonation

Chiral Lewis Acid-Catalyzed Norrish Type II Cyclization to Synthesize α-Oxazolidinones via Enantioselective Protonation

Copper-Catalyzed Ligand-Controlled Selective Borocarbonylation of α-Substituted Styrenes Toward β-Boryl Aldehydes and Cyclopropyl Boronate Esters

Copper-Catalyzed Ligand-Controlled Selective Borocarbonylation of α-Substituted Styrenes Toward β-Boryl Aldehydes and Cyclopropyl Boronate Esters

Novel Strategy for Non-Aqueous Bioconjugation of Substituted Phenyl-1,2,4-triazole-3,5-dione Analogues.

A novel 4-[4-(pentafluoro-λ⁶-sulfanyl)phenyl]-1,2,4-triazole-3,5-dione (5a) was synthesised as a potential [18F]radio-prosthetic group for radiolabelling peptides and proteins via selective bioconjugation with the phenolic side chains of tyrosine residues. Preliminary conjugation tests revealed the rapid hydrolysis of 5a under semi-aqueous conditions; these results led to further investigation into the electronic substituent effects of PTAD derivatives and corresponding hydrolytic stabilities. Five derivatives of 5a with para substituents of varying electron donating and withdrawing effects were synthesised for the investigation. The bioconjugation of these derivatives with model tyrosine was monitored in both aqueous and organic media in the presence of a variety of catalysts. From these investigations, we have found HFIP to be an effective catalyst when used in tandem with DCM as a solvent to give PTAD-tyrosine conjugate products (6a–f) in satisfactory to good yields (54–79%), whereas analogous reactions performed in acetonitrile were unsuccessful. The discovery of this system has allowed for the successful conjugation of electron-deficient PTAD derivatives to tyrosine, which would otherwise be unachievable under aqueous reaction conditions. The inclusion of these electron-deficient, fluorinated PTAD derivatives for use in the PTAD-tyrosine conjugation will hopefully broaden their applicability within fields such as 19F-MRI and PET imaging.

Synthesis, reaction, antimicrobial, and docking study of new chalcones incorporating isoquinoline moiety

Reaction of isoquinoline 1 with hydrazonoyl chlorides 2A–E gave the corresponding triazoloisoquinolines 4A–E. The latter products 4A–E were reacted with 4-(piperidin-1-yl)benzaldehyde 5a and 4-morpholinobenzaldehyde 5b to afford the corresponding chalcones 6a,b. Some of chalcones 6 were reacted with hydrazine hydrate in refluxing ethanol to give the corresponding 8,9-dimethoxy-1-aryl-4,5-dihydro-1H-pyrazol-3-yl-1,5,6,10b-tetrahydro-[1,2,4]triazolo[3,4-a]isoquinoline derivatives 7A–C. Antimicrobial studies were performed using gram-negative bacteria (Escherichia coli) and (Klebsiella pneumonia), a gram-positive bacteria (Streptococcus mutans) and (Staphylococcus aureus), filamentous fungus (Asperagillus Nigar) and yeast (Candida albicans). Data revealed that chalcone 6Aa achieved the lowest MIC values (high efficient derivative) against the sensitive bacterial strain E. coli with MIC value 130 µg/ml. The most effective compound 6Aa, which demonstrated the highest binding affinity toward tested protein [thymidine phosphorylase enzyme, (PDB ID:4EAD)], was docked using MOE 2014.09 software.

Enantioselective Synthesis of α-Alkenylated γ-Lactam Enabled by Ni-Catalyzed 1,4-Arylcarbamoylation of 1,3-Dienes

Enantioselective Synthesis of α-Alkenylated γ-Lactam Enabled by Ni-Catalyzed 1,4-Arylcarbamoylation of 1,3-Dienes

Visible-Light-Induced [4+1] Cyclization-Aromatization of Acylsilanes and α,β-Unsaturated Ketones

Visible-Light-Induced [4+1] Cyclization-Aromatization of Acylsilanes and α,β-Unsaturated Ketones

Nucleophilic substitution pathways in the reactions of 3-amino-1-propanol with mono substituted cyclotriphosphazene derivatives

This study was planned to determine the reaction pathway and mechanism in the nucleophilic substitution reactions of cyclotriphosphazene derivatives with amino alcohol and to put an end to the spiro versus ansa dilemma. Three different monosubstituted cyclotriphosphazene compounds N3P3Cl5R [R = -NHPri (1a), -NMe2 (1b) and R = -OMe (1c)] were reacted with 3-amino-1-propanol. These reactions led to new cyclotriphosphazenes bearing aminoalkoxy: single-bridged (2a), mono-ansa (3a, 3c) and mono-spiro (4b-I, 4b-II and 4c-I). The structures of isolated products (2a, 3a, 4b-I, 4c-I and 4c-II) were characterized by elemental analysis, mass spectrometry and (1H, 13C and 31P) NMR spectroscopies. The structures of 3a, 4b-I and 4c-I were further determined by single crystal X-Ray crystallography. The functional groups on cyclotriphosphazenes provide an opportunity to generate both ansa and spiro isomers which can be formed by intramolecular pathway. Additionally, the formation of bridged products can also be explained by intermolecular route, depending on the orientation effect of the substituted groups on incoming amino alcohols.

Chemical evaluation and application of cinnamaldehyde-derived curcumins as potential fingerprint development agents

Curcumines comprise a class of substances widely applied in several areas including Papiloscopy which studies human identification through fingerprints. Fingerprints are important physical evidences in criminal investigations generally requiring powders in order to visualize latent fingerprints. In this sense, the aim of this study was to characterize curcumine analogues derived from cinnamaldehyde and to evaluate their efficiency as fingerprint powder. Results showed that the products (1a, 1b and 1c) had a yield above 52% being identified by Infrared spectrophotometer due to the presence of C=H, CH, C=O, C=C and CC bonds which are characteristic moieties of the synthesized curcumins. Likewise, it was possible to identify the molecules by Gas Chromatography-Mass Spectrometry through their respective molecular masses (m/z), and by Nuclear Magnetic Resonance. Regarding fingerprints development, application of 1b allowed the visualization of papillary ridges and their details. Scanning Electron Microscopy analysis showed the interaction between powder 1b, the composition of the fingerprint and the substrate. Moreover, particle size analysis indicated that powder 1b (62.41 µm) had smaller particle size compared to the Gold® standard powder (116.66 µm). Therefore, curcumin derivatives were satisfactorily synthesized and characterized as well as powder 1b was able to adequately develop latent fingerprints being an alternative potential to commercial powders.

Catalytic [2+2+2] Tandem Cyclization with Alkyl Substituted Methylene Malonate Enabling Concise Total Synthesis of Four Malagasy Alkaloids

Catalytic [2+2+2] Tandem Cyclization with Alkyl Substituted Methylene Malonate Enabling Concise Total Synthesis of Four Malagasy Alkaloids

Design, Synthesis, and Applications of ortho -Sulfur Substituted Arylphosphanes

Design, Synthesis, and Applications of <i>ortho</i> -Sulfur Substituted Arylphosphanes

PTSA-catalyzed selective synthesis and antibacterial evaluation of 1,2-disubstituted benzimidazoles.

Herein, we developed a convenient and efficient method via protonation of p-toluenesulfonic acid promoted cyclocondensation of o-phenylenediamine and aldehydes for selectively synthesizing 1,2-disubstituted benzimidazoles. This method displayed broad substrate adaptability and afforded the desired products in moderate to excellent yield in short reaction time. The effect of different substituents on the yield was investigated by extending optimum reaction conditions, which was further confirmed by theoretical calculations. It suggested that the surface electrostatic potential of oxygen atom and nitrogen atom on the substrates played important role in the synthesis of 1,2-disubstituted benzimidazoles. Besides, the crystal structure of compound 2t in the orthorhombic space group P2(1)/c was presented. Also, the anti-mycolicibacterium smegmatis (MC2155) activity was evaluated using rifampicin as a positive control. The products (2a, 2b, 2c, 2i, 2j, 2k, 2m) showed good antibacterial activities which were comparable to rifampicin.

4-Chlorophenyl-N-furfuryl-1,2,4-triazole Methylacetamides as Significant 15-Lipoxygenase Inhibitors: an Efficient Approach for Finding Lead Anti-inflammatory Compounds.

Lipoxygenases (LOXs) are a class of enzymes that catalyze the production of pro-inflammatory mediators, such as leukotrienes and lipoxins, via an arachidonic acid cascade as soon as they are released from the membrane phospholipids after tissue injury. In continuation of our efforts in search for new LOX inhibitors, a series of chlorophenyl-furfuryl-based 1,2,4-triazole derivatives were prepared and evaluated for their 15-LOX inhibitory activities. A simple precursor, 4-chlorobenzoic acid (a), was consecutively transformed into benzoate (1), hydrazide (2), semicarbazide (3), and N-furfuryl 5-(4-chlorobenzyl)-4H-1,2,4-triazole (4), which when further merged with electrophiles (6a–o) resulted in end products (7a–o). The structural elucidations of the newly synthesized compounds (7a–o) were carried out by Fourier transform infrared, 1H-, 13C NMR spectroscopy, EI-MS, and HR-EI-MS spectrometry. The inhibitive capability of compounds (7a–o) on soybean 15-LOX was performed in vitro using the chemiluminescence method. The compounds 7k, 7o, 7m, 7b, and 7i demonstrated potent activities (IC50 17.43 ± 0.38, 19.35 ± 0.71, 23.59 ± 0.68, 26.35 ± 0.62, and 27.53 ± 0.82 μM, respectively). These compounds revealed 79.5 to 98.8% cellular viability as measured by the MTT assay at 0.25 mM concentration. The structure-activity relationship (SAR) studies showed that the positions and the nature of substituents bonded to the phenyl ring are important in the determination of 15-LOX inhibitory activities. ADME, in silico, and density functional theory studies supported the evidence as yet another class of triazoles with potential lead properties in search for anti-LOX compounds with a safe gastrointestinal safety profile for various inflammatory diseases. Further work is in progress on the synthesis of more derivatives in search for anti-inflammatory agents.

Synthesis of novel azole functionalized trifluoromethyl pyrido[2,3-d] pyrimidinone derivatives and their antimicrobial activity

Novel azole functionalized pyrido[2,3-d] pyrimidinone derivatives 6a-l were prepared starting from 2-Amino- 6-(thiophen-2-yl)-4-(trifluoromethyl)nicotinonitrile 1 reacting with trifluoroacetic acid in the presence of conc. H2SO4 and further reaction with bromoethyl acetate to obtain 3a and 3b. Compounds 3a and 3b further reacted with hydrazine hydrate to afford hydrazide compounds 4a and 4b. Compounds 4a and 4b on treating with phenylisothiocyanate give compound 5a and b. Compound 5a and 5b on reaction with different reagents (NaOH, H2SO4 and N2H4.H2O) produced different azole-substituted (triazolothione, thiadiazole, triazole) functionalized trifluoromethyl pyrido[2,3-d] pyrimidinone derivatives 6a-l respectively. All the products 6a–l were screened against gram +ve, gram –ve bacteria and fungal strains. Compounds 6ad showed promising activity against Bacillus subtilis microbial-type culture collection (MTCC) 121 at &lt;25.6 micromolar concentration. Promising compounds were further screened for minimum bactericidal concentration against B. subtilis MTCC 121 using ciprofloxacin as standard reference and found to show very good activity. These compounds also screened for biofilm inhibition activity against B. subtilis MTCC 121 using erythromycin as standard confirming the high activity.

Catalyst-free nitration of the aliphatic C[sbnd]H bonds of tertiary β-keto esters with tert-butyl nitrite: Access to α-quaternary α-amino acid precursors

An efficient catalyst-free direct nitration of the CH bonds of tertiary β-keto esters using tert-butyl nitrite as a nitrating reagent is described. This radical nitration protocol tolerants diverse functional groups, leading to the preparation of linear and cyclic α-nitro-β-keto ester derivatives in good to excellent yields under mild conditions. In addition, the nitration product 3a was applied to the concise synthesis of α-quaternary α-amino acid 4 in the presence of zinc power and acetic acid.

Assembling high nitrogen isomeric energetic molecules via a lithium-mediated concerted [2 + 3] reaction of two diazo compounds

The search for high nitrogen isomeric energetic molecules and comparison of their structure–property relationship are always attractive in the field of energetic materials. In this paper, a novel lithium-mediated concerted [2 + 3] reaction with two diazo compounds has been accomplished which leads to the simultaneous formation of two isomeric cyanotetrazoles (2a and 2b). The cyano group in cyanotetrazoles was further converted to tetrazole or tetrazole N-oxide to form tricyclic heterocyclic products (3a, 3b, 7a, and 7b). The energetic properties of the compounds were studied. A representative compound 3a (Td = 220 °C, D = 9052 m s−1, IS = 13 J, FS = 200 N) has better detonation performances, higher thermal stability and lower mechanical sensitivities than RDX, which is expected to serve as a potential energetic material.

Supramolecular Template-Assisted Catalytic [2+2] Photocycloaddition in Homogeneous Solution

Supramolecular Template-Assisted Catalytic [2+2] Photocycloaddition in Homogeneous Solution