Search

The first study on oxidative sulfonamidation of camphene is presented. By varying the reaction conditions, the nature of the sulfonamide, the oxidizing agent, the ratio of the reagents, and the solvent, it is possible to control not only the direction of amidation of the double bond of camphene, leading to the formation of the corresponding amides or amidines, but also the rearrangement or retention of the camphene structure. In the NIS-induced reaction, no rearrangement occurs, leading to N-sulfonylamidine derivatives of isocamphane. The NBS-induced reaction takes place with solvent (acetonitrile) intersection and with or without rearrangement, resulting in N-sulfonylamine with isocamphane or camphane motif, depending, strikingly, on the ratio of the reactants. A mechanism that explains the diversity of products has been proposed and confirmed by theoretical calculations. It includes various intermediates formed via electrophilic addition of a halogen, such as an open carbocation for Br+, or the anchimerically assisted iodonium cation for I+. Additionally, the basicity of the reaction medium can change depending on the ratio of the reagents. For example, in CH2Cl2, which is incapable of being trapped by the intermediate cations, the formation of bromosulfonamide occurs only with triflamide due to the highest halogening activity of the intermediate CF3SO2NHBr. The structure of the products formed in up to 96% yield was proved by NMR, HRMS and, for the key products, by X-ray analysis. When performing the NBS-induced bromosulfonation of camphene using triflamide with subsequent addition of potassium carbonate (K2CO3), no dehydrobromination occurred. However, when using cesium fluoride (CsF) as a base, an unexpected quinazoline product was obtained. This opens up the possibility for further transformations. [ABSTRACT FROM AUTHOR]

The Ce0.5Y0.35Tb0.15F3 nanoparticles with a CeF3 hexagonal structure were synthesized using the co-precipitation technique. The average nanoparticle diameter was 14 ± 1 nm. The luminescence decay curves of the Ce0.5Y0.35Tb0.15F3 nanoparticles (λem = 541 nm, 5D4–7F5 transition of Tb3+) conjugated with Radachlorin using polyvinylpyrrolidone coating as well as without Radachlorin were detected. Efficient nonradiative energy transfer from Tb3+ to the Radachlorin was demonstrated. The maximum energy transfer coefficients for the nanoparticles conjugated with Radachlorin via polyvinylpyrrolidone and without the coating were 82% and 55%, respectively. The average distance between the nanoparticle surface and Radachlorin was R0 = 4.5 nm. The best results for X-ray-induced cytotoxicity were observed for the NP-PVP-Rch sample at the lowest Rch concentration. In particular, after X-ray irradiation, the survival of A549 human lung carcinoma cells decreased by ~12%. [ABSTRACT FROM AUTHOR]

The reaction of butyryl chloride with ethynylbenzene in the presence of AlCl3 afforded a mixture of the Z/E‐isomers of 1‐chloro‐2‐phenylhex‐1‐en‐3‐one. 1,2‐Diphenylethyne under these conditions gave a novel polycarbocycle core, 6aH‐benzo[a]fluorene. The chemical structure of 11‐chloro‐5,6‐diphenyl‐6a‐propyl‐6aH‐benzo[a]fluorene was established by means of IE‐MS, 1H, 13C NMR, COSY, HSQC, HMBC, and 2D INADEQUATE technique. [ABSTRACT FROM AUTHOR]

Secondary phosphine chalcogenides mildly (no catalysts and solvents, 20–65 °C, 0.25–65.5 h) react with aldimines to deliver the hitherto unknown α‐aminophosphine oxides, sulfides and selenides in good to excellent yields. [ABSTRACT FROM AUTHOR]

The one-pot efficient synthesis of novel functionalized organoselenium compound by bis-alkoxyselenenylation of alkenes with selenium dibromide and alcohols was developed. The reaction of the selenium dibromide with cyclopentene or cyclohexene in the system alcohol/sodium bicarbonate/methylene chloride at room temperature afforded bis(2-alkoxycycloalkyl) selenides in 90–99% yields. The regioselective and efficient method for bis-alkoxylation of terminal alkenes was developed based on the addition of selenium dibromide with 1-alkenes in acetonitrile followed by refluxing of addition products in alcohols in the presence of traces of sulfuric acid. This method made it possible to selectively obtain bis(2-alkoxyalkyl) selenides in 94–98% yields. [ABSTRACT FROM AUTHOR]

A variety of tetra‐, di‐ and monobromo derivatives of dienoates were prepared from parent polyunsaturated esters under mild conditions. According to proposed protocol the target bromoesters were easily obtained as a rule in good yields and high selectivity. [ABSTRACT FROM AUTHOR]

A facile one-pot synthesis of trifluoromethylated pyrimidines has been achieved by the treatment of fluorinated 2-bromoenones with aryl- and alkylamidines. The assembly of pyrimidine core proceeds by the cascade reactions via aza-Michael addition–intramolecular cyclization–dehydrohalogenation/dehydration sequence. This strategy is featured by high selectivity and mild reaction conditions giving the target heterocycles in high yields (up to 99%). The unique influence of trifluoromethyl group on the reaction path is demonstrated. [ABSTRACT FROM AUTHOR]

The catalyst- and solvent-free reaction between bis(fluoroalkyl) phosphonates and aldimines occurs under mild conditions (20–22 °C, 0.25–4 h) to afford a new family of α-amino polyfluoroalkylphosphonates in up to quantitative yields. [ABSTRACT FROM AUTHOR]

A novel methodology to accelerate annulation reactions leading to condensed selenium heterocycles was developed. The reactions of selenium dihalides with methyleugenol, allyl thymyl ether, allyl 1-naphthyl and 1-naphthyl propargyl ethers were carried out in the presence of alcohols, which considerably accelerated the annulation reactions. In solvent systems CH2Cl2/MeOH or CHCl3/MeOH, the reactions proceeded as annulation–methoxylation affording condensed methoxylated heterocycles. In the presence of isopropanol, the reactions were not accompanied by alkoxylation giving condensed halogen-containing products. The annulation reaction of selenium dihalides with 1-naphthyl propargyl ether included stereoselective anti-addition to the triple bond. The efficient selective synthesis of the first representatives of novel families of condensed selenium heterocycles with promising biological activity was developed. [ABSTRACT FROM AUTHOR]

Highly efficient stereoselective syntheses of novel bis(E-2-chlorovinyl) selenides and bis(E-2-bromovinyl) selenides in quantitative yields by reactions of selenium dichloride and dibromide with alkynes were developed. The reactions proceeded at room temperature as anti-addition giving products exclusively with (E)-stereochemistry. The glutathione peroxidase-like activity of the obtained products was estimated and compounds with high activity were found. The influence of substituents in the products on their glutathione peroxidase-like activity was discussed. [ABSTRACT FROM AUTHOR]

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO3 affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed. [ABSTRACT FROM AUTHOR]

It has been found that both eugenol and isoeugenol derivatives reacted with 2-pyridinesulfenyl and 2-pyridineselenenyl halides in a regioselective mode affording products with opposite regiochemistry. Synthesis of new families of 2H,3H-[1,3]thia- and -selenazolo[3,2-a]pyridin-4-ium heterocycles has been developed by annulation reactions of 2-pyridinechalcogenyl halides with natural compounds (eugenol, isoeugenol, methyl eugenol, methyl isoeugenol, acetyl eugenol, trans-anethole) and their structural analogs. The influence of the substrate structure and the nature of halogen on the product yields are studied. The 2-pyridinesulfenyl and 2-pyridineselenenyl chlorides are more efficient reagents compared to corresponding bromides. The obtained condensed heterocycles are novel water-soluble functionalized compounds with promising biological activity. [ABSTRACT FROM AUTHOR]

Introduction: A simple method for the preparation of 5-(trifluoroacetyl)imidazoles was elaborated., Methods: The reaction of trifluoromethyl(α-bromoalkenyl)ketones with benzimidamides was employed to afford the target heterocycles in good yields., Results: The assembly of imidazole core proceeds via aza-Michael adduct formation followed by intramolecular nucleophilic substitution and spontaneous aromatization as an oxidation sequence., Conclusion: The yields of target imidazoles can be improved by the use of soft oxidizing agents., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Highly efficient stereoselective syntheses of novel bis( E -2-chlorovinyl) selenides and bis( E -2-bromovinyl) selenides in quantitative yields by reactions of selenium dichloride and dibromide with alkynes were developed. The reactions proceeded at room temperature as anti -addition giving products exclusively with ( E )-stereochemistry. The glutathione peroxidase-like activity of the obtained products was estimated and compounds with high activity were found. The influence of substituents in the products on their glutathione peroxidase-like activity was discussed.

It has been found that both eugenol and isoeugenol derivatives reacted with 2-pyridinesulfenyl and 2-pyridineselenenyl halides in a regioselective mode affording products with opposite regiochemistry. Synthesis of new families of 2 H ,3 H -[1,3]thia- and -selenazolo[3,2- a ]pyridin-4-ium heterocycles has been developed by annulation reactions of 2-pyridinechalcogenyl halides with natural compounds (eugenol, isoeugenol, methyl eugenol, methyl isoeugenol, acetyl eugenol, trans-anethole) and their structural analogs. The influence of the substrate structure and the nature of halogen on the product yields are studied. The 2-pyridinesulfenyl and 2-pyridineselenenyl chlorides are more efficient reagents compared to corresponding bromides. The obtained condensed heterocycles are novel water-soluble functionalized compounds with promising biological activity.