Experimental and Computational NMR Studies of Large Alkaloids Exemplified With Vindoline Trimer: Advantages and Limitations.

The complete H and C NMR assignments of a trimeric vindoline together with its individual components, dimeric vindolicine and monomeric vindoline, are performed based on a thorough analysis of the ROESY, COSY, HSQC, and HMBC spectra in combination with the state-of-the-art quantum-chemical calculations. A spatial structure of vindoline trimer is determined by means of computational conformational analysis in combination with the probability distribution map of its basic conformers. On the example of monoterpene indole alkaloid, the trimer vindoline, the present study reveals the power of modern computational NMR to perform identification and stereochemical studies of large natural compounds with some limitations, which may arise in the quantum chemical computing workflow.

Photo- and X-ray Induced Cytotoxicity of CeF-YF-TbF Nanoparticle-Polyvinylpyrrolidone-"Radachlorin" Composites for Combined Photodynamic Therapy.

The CeYTbF nanoparticles with a CeF hexagonal structure were synthesized using the co-precipitation technique. The average nanoparticle diameter was 14 ± 1 nm. The luminescence decay curves of the CeYTbF nanoparticles (λ = 541 nm, D-F transition of Tb) conjugated with Radachlorin using polyvinylpyrrolidone coating as well as without Radachlorin were detected.

6aH-Benzo[α]fluorene: NMR evidence of the unexpected product of the reaction of butyryl chloride with 1,2-diphenylacetylene.

The reaction of butyryl chloride with ethynylbenzene in the presence of AlCl 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, H, C NMR, COSY, HSQC, HMBC, and 2D INADEQUATE technique.

Synthesis of 5-(trifluoroacetyl)imidazoles from Bromoenones and Benzimidamides Aza-Michael Initiated Ring Closure Reaction.

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 aza-Michael adduct formation followed by intramolecular nucleophilic substitution and spontaneous aromatization as an oxidation sequence.

Selenium Dihalides Click Chemistry: Highly Efficient Stereoselective Addition to Alkynes and Evaluation of Glutathione Peroxidase-Like Activity of Bis(-2-halovinyl) Selenides.

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

A Regioselective Synthesis of Novel Functionalized Organochalcogen Compounds by Chalcogenocyclofunctionalization Reactions Based on Chalcogen Halides and Natural Products.

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 NaHCO 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.

Natural Compounds and Their Structural Analogs in Regio- and Stereoselective Synthesis of New Families of Water-Soluble 2,3-[1,3]thia- and -Selenazolo[3,2-]pyridin-4-ium Heterocycles by Annulation Reactions.

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 2,3-[1,3]thia- and -selenazolo[3,2-]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.