Letters in Organic Chemistry - Volume 16, Issue 7, 2019

By using the Piers-Rubinsztajn processes, elastomers, foams, silicone surfactants and copolymers with alkoxy-functional arylamines and ethers can be prepared. The preparation and applications of siloxane-based materials through Piers-Rubinsztajn reaction synthesis pathway have been reviewed.

The synthesis of various N-acetyl-bis-indole compounds has been achieved by one pot reaction of indole and acid chloride in the presence of silica sulfuric acid as a catalyst under microwave irradiation to moderate yields. The reaction has also been studied with different acid chlorides and solvents.

The dimerization of 1-bromo-2-phenylcyclopropanecarbonyl chloride by the use of the zinc/copper couple selectively leads to anti-trans-1,6-diphenyldispiro[2.1.2.1]octane-4,8-dione, the structure and configuration of which are proved by X-ray structure analysis.

Here we report a greener approach for the synthesis of enamines from enols of 1,3-alkyl-2- thioxodihydropyrimidine-4,6(1H,5H)-dione (thiobarbituric acid) acid using ammonium chloride and ethanol as solvents. This protocol removes the need for catalysts or harsh conditions.

The Mn-hydrazone Schiff base encapsulated into NaY has been prepared and characterized as a new heterogeneous catalyst. Elemental analysis, UV-Vis, infrared spectroscopic analysis, diffused reflectance spectroscopy, thermal analysis, small angle X-ray diffraction, and N2 sorption demonstrate the existence of Mn-hydrazone schiff base in the nanopores of zeolite-Y. MnII(Hsal- hrz)/Y, which showed excellent catalytic property in oxidation with various sulfide compounds including important drugs such as adrafinil and modafinil, using hydroperoxide-urea (UHP) as oxidant. Thioanisole conversion was high (98%).

Ionic Liquid assisted efficient synthesis of some 2-aminobenzenethiols has been reported using three different Ionic Liquids (ILs) namely methylimidazolium tetrafluoroborate [MIM]+[BF4]−, methylimidazolium chloride [MIM]+[Cl]− and methylimidazolium nitrate [MIM]+[NO3]−. A comparative study has been carried out for the synthesis of target molecules in the presence and absence of IL, leading to conclusion that maximum yield has been observed with [MIM]+[BF4]−.

C21 steroids glycosides of various deoxysugars have been emerging from genus of Cynanchum. Besides classical C21 glycosides, many C21 glycosides with seco-ring aglycones attracted the extensive attention of many researchers. We conducted a systematic chemical investigation on Cynanchum hancockianum, which led to the isolation of one new seco-ring C21 steroidal glycosides. The new compound was identified as cynaascyriogenin 3-O-β-D-glucopyranosyl-(1-4)-α-L-cymaropyranosy-(1-4)- β-D-cymaropyranosyl-(1-4)-β-D-cymaropyranoside. The cytotoxic activities of the compound were evaluated using the A549 and MCF-7 cell lines, respectively. The IC50 values of the compound were 41.3 and 67.1μM, respectively. This is the first report on the isolation of seco-ring C21 steroidal glycosides from Cynanchum hancockianum.

The synthesis of 4-amino-2-arylamino-5-(benzofuran-2-oyl)thiazoles 4a-h, as example of 2,4-diaminothiazole-benzofuran hybrids and an evaluation of their antidiabetic activity, by in vitro and computational methods, are reported. The synthesis of these diaminothiazoles was achieved mechano chemically by a rapid solvent-less method. Their antidiabetic activity was assessed by α-glucosidase and α-amylase inhibition assays. The, IC50 value for α-glucosidase inhibition by 4-amino-5- (benzofuran-2-oyl)-2-(4-methoxyphenylamino)thiazole (4d) was found to be 20.04 μM and the IC50 value for α-amylase inhibition, 195.03 μM, whereas the corresponding values for reference acarbose were 53.38 μM and 502.03 μM, respectively. Molecular docking studies at the active sites of α- glucosidase and α-amylase showed that among the diaminothiazoles 4a-h now studied, 4-amino-5- (benzofuran-2-oyl)-2-(4-methoxyphenylamino)thiazole (4d) has the highest D-scores of -8.63 and -8.08 for α-glucosidase and for α-amylase, with binding energies -47.76 and -19.73 kcal/mol, respectively.

Isothiocyanate functional group (-N=C=S) is widely accepted as an important moiety for anti- cancer effects of naturally occurring isothiocyanate compounds (ITCs). Herein, a series of diisothiocyanate (diITCs) derivatives were synthesized and evaluated in antiproliferative assays on A549 human non-small cell lung cancer and IMR90 human foetal lung cell lines for structure-activity relationship (SAR) and cancer cell selectivity studies. Results showed that aliphatic and benzylic diITCs were more cytotoxic to A549 cells than natural ITCs; benzyl isothiocyanate (BITC) and phenyl isothiocyanate (PITC), and a currently available anticancer drug; etoposide. Aromatic diITCs were not as active. Notably, most of the diITCs reported in this work were significantly more selective than etoposide to inhibit proliferation of the cancer cells (A549) over the normal cells (IMR90). This study demonstrated a guideline to modify chemical structures of diITCs for anti-NSCLC agents.

A series of novel derivatives based on 2-amino-substituted 4-methylpyrimidin-4-ols were synthesized by simple, accessible and efficient methods. 4-N-triazolyl derivatives were obtained from the corresponding 4-chloro derivatives, and O-substituted products, including compounds with a combination of the pyrimidine and oxadiazole rings in the molecule, were synthesized from the sodium salts of 2-amino-substituted pyrimidin-4-ols. The synthesized compounds showed a pronounced stimulating action on plants growth. Their growth stimulant activities were in the range of 46-93% compared to heteroauxin.

A straightforward strategy for the synthesis of N-sulfonyl imine derivatives from sulfonamides and aryl aldehydes utilizing Silica-supported zinc chloride (ZnCl2/SiO2, silzic) as a catalyst under solvent-free conditions has been developed. 2-Arylbenzothiazole derivatives were also synthesized by the reaction of 2-aminothiophenol with aryl aldehydes under the same conditions. This procedure has advantages of high yields, mild reaction condition, simple procedure, low cost, and simplicity of workup. The catalyst has the same efficiency on its reuse up to three times.

Corannulene (C20H10) and its fluorinated derivatives, C20H10-xFx (x=1-10), are investigated at the B3LYP/6-31G level of density functional theory. The degree of electron delocalization is evaluated using Nucleus Independent Chemical Shift (NICS) method, Electric Field Gradient (EFG) method and factor of Ellipticity (). In this study, the benzene is the scale of comparison as a more aromatic structure. The aromaticity has been evaluated at three points of structures; center of five-member ring (5-MR), center of fluorine-substituted ring (6-MR), and center of other six-member rings. This comparison shows that substitution of fluorine for four and five hydrogen atoms in the Corannulene structure, C20H10-xFx (x=4, 5), results in more aromaticity compared to the other substitutions, and C20H10 and C20H10-xFx (x=1, 3) are more antiaromatic. It seems that the EFG method is more reliable for forecasting the aromaticity of structures, than NICS method. The factor of Ellipticity and bond lengths resulted from Atom in Molecule (AIM) analysis support the EFG method.

An efficient synthesis of biologically important benzylidene-indolin-2-one derivatives using meglumine as green catalyst and ethanol:water as reaction media at 78°C has been developed. The effects of reaction conditions such as solvents, temperature, and amount of catalyst were investigated. The present methodology offers many advantages such as simple procedure, less time taking to complete the reaction, high yield of products, and clean reaction profile.