Letters in Organic Chemistry - Volume 18, Issue 8, 2021

Treatment of 2-aminophenol (or 2-aminothiophenol) with aromatic aldehydes in the presence of phosphomolybdic acid on silica at room temperature affords the corresponding benzoxazoles (or benzothiazoles) in excellent yields (88-96%) under heterogeneous conditions. Benzoxazoles and benzothiazoles are formed in less than 10 min.

The main component of the sex pheromone of many lepidopteran pests, (4E,10Z)-4,10- tetradecadienyl acetate (1) has been synthesized stereoselectively by using a simple route with 4- pentynol as a starting material. The stereoselective formation of the 4E double bond is based on the stereospecific reduction of internal alkyne with lithium aluminium hydride (LAH) while Wittig reaction was used to achieve 10Z double bond in the target pheromone component. The GC purity of the final acetate was achieved 97.87% while isomeric purities are more than 99%. The green chemistry principle shows a new concept towards the multistep pheromone synthesis via green metrics calculations.

A new solid catalyst was synthesized from an ionic liquid and heterogenised by changing the anion reaction. The new heterogeneous acidic catalyst was characterized by SEM images, EDS analysis, AFM images, Ft-IR, HNMR, ¹³CNMR and Mass Spectroscopy. It was applied to the synthesis of tri-arylmethanes throughout one-pot tri-component reactions among aromatic aldehydes, N,N-dimethylaniline and other carbonic nucleophiles such as anisole and indole. Hence, the synthesis of convenient and inexpensive micro-heterogeneous catalyst was introduced, the efficiency of which was confirmed. Also, various useful products were synthesized throughout this simple and clean procedure.

The Friedel-Crafts alkylation of indole with ketones and aldehydes had been developed to prepare 3,3’-diindolylmethanes using iodine or NCS as catalysts. Two mild and efficient catalysis systems were provided for the activation of carbonyl compounds and indoles. The reaction proceeded smoothly in ethanol to produce the corresponding products with good to excellent yields. Furtherly, the mechanism was speculated.

The catalytic activity of Schiff base Co(II), Ni(II), Cu(II) and Zn(II) transition metal complexes was tested for N-Acylation of heterocycles with acetyl chloride. It is observed that all the complexes worked as efficient catalysts. The structural type of complexes was studied by an Xray powder diffractogram (XRD). The mixed ligand complexes with PPh3 ligand show greater activity as compared to Phen complexes and Schiff base complexes. Especially complex [Ni(L)(PPh3)2Cl2] efficiently worked as a catalyst because of high thermal stability (TGA-DSC) and large catalytic surface area (BET).

Triazoles are famous as an antifungal agent. Itraconazole and fluconazole are the best examples of antifungal drugs available in the market, which consist of an active triazole moiety. Pyrimidines are also bioactive molecules which shows multiple bioactivity. It’s an effort to synthesize pyrimidine clubbed triazole to enhance bioactivity. To synthesize new active pyrimidine clubbed triazole biomolecule and to evaluate these new products for better drug potential as antimicrobial, antituberculosis, antimalarial, and anti-protozoal, N-[4-(substituted phenyl)-6- (substituted aryl) pyrimidine-2-yl]-2-[(4H-1,2,4-triazol-4-yl)amino]acetamide(3A-J) were synthesized by different method such as cyclization, condensation, purification and crystallization. The newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral analysis and screened for antibacterial, antifungal, anti-tuberculosis, antimalarial, and antiprotozoal activities. These compounds satisfied the bioactive response and simple way for the synthesis.

Pd/C catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids and transfer hydrogenation of quinolines had been developed for the synthesis of 1,2,3,4- tetrahydroquinolines. These two processes were implemented smoothly using Pd/C (0.9 mol%) as a catalyst with ammonium formate as a hydrogen source in ethanol at 80 °C. The reaction system can also be applied to transfer hydrogenation of benzo[h]quinoline and 2,9-dimethyl-1,10- phenanthroline with good to excellent yields. And the gram scale and recycling of catalyst had been tested with good results. Furthermore, the mechanism of Pd/C catalyzed reduction of quinoline carboxylic acids and quinolines had been proposed.

An inexpensive and eco-friendly Wittig olefination protocol has been developed to prepare novel (E)-5-styrylpyrimidines. The reaction of pyrimidine phosphonium ylide with different aryl/heteroaryl aldehydes underwent smoothly in the presence of sodium tripolyphosphate (STPP) in aqueous condition giving (E)-5-styrylpyrimidines (10a-t) in very high yields (77-96 %).

In the current work, the adsorption of Sulfanilamide (SLF) drug over B12N12 and Al12N12 fullerenes was studied using DFT and TDDFT calculations at the M06-2X/6-31+G** level in the solvent water for the first time. The adsorption effect of the SLF on the bond length, electronic properties such as charge analysis, frontier molecular orbital (FMO), dipole moment and optical properties of B12N12 and Al12N12 fullerenes, was investigated. The UV absorption spectra were calculated for the study of the significant changes taking place in interactions between SLF and B12N12 and Al12N12 fullerenes. According to charge analysis, it is found that charge transfer occurs from SLF drug to fullerenes and from fullerene to SLF drug. The analysis of the LOL and ELF showed that the N-B and O-B bonds are greater than the other bonds, representing higher electron density localization and stronger covalent characteristic. The adsorption of the SLF from the head of the N atom of sulfonamide group on the surface of B12N12 with the lower energy gap (EG) was more considerable than the head O atom and the N atom of NH2-Ar group. It is found that the applied B12N12 fullerene can be suitable as a drug carrier for the delivery of SLF drugs.

Conformational behaviors of 2, 5-dimethoxy-2,5-dimethyl-1,4-dithiane (compound 1) and 2,5-dimethyl-2,5-bis (methylthio)-1,4-dithiane (compound 2) were investigated by computational methods including B3LYP/6-311+G** and M06-2X/6-311+G** levels of theory and NBO analysis. The stereoelectronic effect of axial, axial (ax, ax) and equatorial, equatorial (eq, eq) conformations was studied using NBO analysis. Using NBO analysis, the values of the stereoelectronic effects were calculated through the energy of stability associated with the electron transfers of compounds 1 and 2. The results showed that the eq, eq conformations of the studied compounds were more stable than their corresponding ax, ax conformations, and LP2X→σS1-C2 and LP2S→σ*C2-X electron transfers play important roles in the conformational behavior of the studied compounds. The main purpose of the present work was to study the effects of stereoelectronic interactions and steric on the conformational superiority of the di-methoxy (compound 1) and di-thiomethyl compounds (compound 2). Thus, the values of resonance stability energy, non-diagonal elements, and orbital populations were investigated. Also, active electrophilic and nucleophilic centers were identified using fronting orbitals analysis obtained by DFT methods. The electrostatic potential maps of the title compounds were investigated at the B3LYP/6-311+G* level of theory. All of the NMR parameters and geometrical properties of both compounds were determined in this study.