Letters in Organic Chemistry - Volume 17, Issue 5, 2020

The tropical plant C. formosum ssp. pruniflorum belongs to family Clusiaceae, which is native to Southeast Asia countries. Phytochemical investigations on this plant showed interesting secondary metabolites, comprising the main classes of xanthones, anthraquinones, flavonoids, phenolics, and triterpenoids. Biological assessments established the wide spectrum of properties, either the extracts or isolated compounds have been becoming valuable resources, constituents from C. formosum ssp. pruniflorum were used for anti-bacteria, anti-inflammation, anti-cancer, or neuroprotective and vascular protective activities. The long history of traditional application has confirmed the prospect in use, this herbal plant was consumed as a combination tea or to treat skin wound healing, fever, cough, ulcer, diarrhea, internal bleeding, stomachic and diuretic effects, and food poisoning.

Among various classes of Photoluminescent (PL) compounds, soft-matter based materials in which chromophores are embedded in a Liquid-Crystal (LC) host polymer prove to be very attractive in the production of flexible panels and on-off temperature switches. Actually, the obtainment of low cost, easily synthesizable, and stable organic molecules soluble in the LC matrix is a challenge for both scholars and technologists. Here we describe the synthesis of two new emissive dyes based on a dicyanophenylenevinylene and on a bis-azobenzene core whose PL properties were investigated as neat solids, in solution, and in particular in a dye-doped LC nematic polymer often employed in PDLC applications. 1H NMR and 13C NMR spectroscopy allow the characterization of all compounds Their thermotropic liquid- crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. Photoluminescence properties were characterized by fluorescence spectra.

A new series of 3-(3,4,5-trimethoxyphenyl)-5-(2-(5-arylbenzo[b]thiophen-3-yl)oxa zol-5- yl)isoxazole derivatives were designed and synthesized. All these derivatives were evaluated for their anticancer activity against various human cancer cell lines such as MCF-7 (breast cancer), A549 (lung cancer), DU-145 (prostate cancer) and MDA MB-231 (breast cancer)-four human cancer cell lines by using MTT assay. Here, etoposide was used as a standard reference drug and most of the compounds were exhibited good anticancer activity with respect to cell lines. Among all compounds, five compounds 11b, 11c, 11f, 11i and 11j showed more potent activity than standard drug, in which, compound 11f was the most promising compound.

A novel library of 1,2,4-oxadiazole bearing isoxazole-pyrazole derivatives (13a-j) were designed, synthesized and evaluated for their anticancer activity towards MCF-7 (breast cancer), A549 (lung cancer), DU-145 (prostate cancer) and MDA MB-231 (breast cancer) human cancer cell lines by MTT assay. Here etoposide used as standard drug. Among them, five compounds (13b, 13c, 13d, 13h and 13i) were exhibited more potent activity. In which compound 13h was the most promising compound against all cell lines MCF-7, A549, DU-145 and MDA MB-231.

An efficient procedure for the synthesis of fused pyrano[4,3-b]chromene derivatives via three-component condensation reaction of aromatic aldehydes, 2-naphthol and 4-hydroxycoumarin, using CuO@RHA/MCM-41 nanocomposite at room temperature, is described. This nanocomposite consists of CuO nanoparticles and MCM-41 matrix obtained from Rice Husk Ash (RHA). This method provides several advantages, such as simple work-up, eco-friendly procedure and short reaction time along with high yields. All of synthesized compounds were characterized by IR, NMR and Elemental analyses.

Tetrahydropyrimidine (THPM) synthesis has an enormous importance in organic chemistry and especially in pharmaceutical applications. Pyrimidines are the most active class of N-containing heterocyclic compounds and have different biological properties. The heterocyclic ring system with a thio group occupy a unique position in medicinal chemistry. This type of compounds play an important role in synthetic drugs and in biological processes. Dihydropyrimidinethione derivatives occur widely in nature. Several modifications of THPM-5-carboxamides have attracted considerable interest of medicinal chemists due to their pharmacological and therapeutic properties. A series of 1,2,3,4-tetrahydro- 2-pyrimidinone/thione derivatives bearing a phenylcarbamoyl group at C-5 position were synthesized by one-pot three-component Biginelli condensation reaction. The reaction of acetoacetanilide as the 1,3-dicarbonyl component with various aromatic aldehydes and urea/thiourea in the presence of a catalytic amount of p-toluenesulfonic acid monohydrate (PTSA·H2O) or concentrated HCl as an efficient catalyst leads to Biginelli compounds. We have prepared eight THPM 5-carboxamide derivatives, four of them are new compounds. Their structures were confirmed by spectroscopic techniques and elemental analysis. These compounds have potential applications in organic synthesis and medicinal chemistry. We have synthesized a series of THPM-5-carboxamides by simple and efficient threecomponent Biginelli condensation reaction. Significant benefits of the present procedure include: a) application of inexpensive, non-toxic, environmentally friendly and easily available catalysts, b) the reactions are easy to carry out without high temperature and the workup is very simple, c) the required reaction times are relatively short (30-80 min with HCl and 8-24 h with PTSA·H2O), d) compatibility with various functional groups, e) the products are isolated in good to excellent yields (50-95%).

Several novel chiral organocatalysts derived from thiazolidines containing amide and thioureia functionalities were synthesized in good yields. These organocatalysts were tested in the asymmetric aldol reaction of acetone with p-nitrobenzaldehyde. Reaction parameters such as reaction time, catalyst loading and solvent were optimized. Products with conversions up to 84% and enantiomeric ratios (er) up to 84.5:15.5 (R:S) were obtained. The effect of several chiral and non-chiral additives on the reactivity and selectivity of the reaction was also evaluated. The reaction was extended to other aromatic aldehydes with the best organocatalyst and when p-bromobenzaldehyde was used, an er of 94.5:5.5 (R:S) was obtained.

Cyclic dipeptides are very important compounds that have a wide range of applications in pharmaceutical chemistry and life sciences. In the current work, the acidity of the side chain of aspartic acid was calculated for various linear and a cyclic dipeptide. pKa values were derived using the thermodynamics cycle and DFT/B3LYP approach. The obtained pKa values show strong acidity for cyclic with respect to linear dipeptides. We found an intramolecular hydrogen bond in cyclic dipeptide structure, which can be used to justify the increasing acidity of the side chain of Asp as compared to linear structures.

From the ethyl acetate extract of the roots of Callerya speciosa (Champ.) Schot. collected in Vietnam, a new oleanane triterpenoid, 22β-acetoxy-3β,24-dihydroxy-12-oleanen-30-oic acid (1), along with three known compounds, medicarpin (2), maackiain (3), and β-sitosterol (4), were obtained. The structure of the new compound was elucidated by HR-MS, 1D and 2D NMR experiments.

There are several protocols for the preparation of bicyclic derivatives; however, some methods use dangerous and require special conditions. The aim of this study was to synthesize a new Dioxaspiro[ bicyclo[3.3.1]nonane-oxabicyclo[6.2.0]-deca-1(10), 8-dien-4-one (compound 8). Compound 8 was prepared using some reactions such as; i) etherification, ii) reduction, iii) amidation, iv) imination and v) 2+2 addition. The chemical structure of 8 and its intermediaries were completely characterized by spectroscopic techniques and elemental analysis. The synthesis showed a yield of 85% for compound 8. In this study, an easy method for the preparation of compound 8 is reported.

The synthesis of 3-(aryl(piperidin-1-yl)methyl)-4-hydroxyquinolin-2(1H)-one derivatives via catalyst-free multicomponent reaction is described. The reaction of 4-hydroxyquinolin-2(1H)-one, piperidine, and 4-chlorobenzaldehyde was carried out in different solvents and under solvent-free conditions at room temperature. The best solvent in terms of the yield and reaction time was found to be dichloromethane. Most substituted benzaldehydes reacted with 4-hydroxyquinolin-2(1H)-one and piperidine to afford corresponding products in good-to-excellent yields. Aldehydes with electronwithdrawing groups were more reactive to exhibit higher reaction rates. However, 2-substituted benzaldehydes did not react with 4-hydroxyquinolin-2(1H)-one and piperidine under the reaction condition. Aldehydes bearing a hydroxyl group failed to produce the corresponding products.