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Several 15,16-epoxy-8,13,14-labdatriene derivatives modified at the C-16 position with a 1,2,4-oxadiazole ring with various substituent in the 5-th position, were obtained via multistep synthesis from 16-formyl derivatives of natural diterpenoid lambertianic acid. The cytotoxicity of furanolabdanoid-based 1,2,4-oxadiazoles was evaluated against human cancer cells (CEM-13, MT-4, U-937, MCF-7, MDA-MB-231, MEL-8) using the conventional MTT assays. All the tested diterpenoid-oxadiazole hybrids displayed better cytotoxic activity then lambertianic acid. The activity and selectivity to the cell line increased even further in the compounds containing a chloromethyl substituent in the 5-th position of the 1,2,4-oxadiazole ring. Two of the synthesized compounds exhibited high cytotoxic activity against lymphoblastoid cell line CEM-13 (GI50 0.08-0.34 μM), which was higher that than of the comparative drug Doxorubicin. The antitumor mechanism may be related to apoptosis induction in U-937, MCF-7, and CEM-13 cells.

Substituted salicylaldehydes (I) react with ethyl diazoacetate (II) to give benzofuran derivatives of type (III).

The data obtained on the regioselectivity of amination are interpreted in terms of DFT/PBE/3Z quantum-chemical calculations.

Title compounds [(VI), (VIII), and (X)] are synthesized starting from harmine (I) via quaternized derivatives (V).

An L-proline-catalyzed regioselective [4+2] cycloaddition of coumarin-3-carboxylic acids (III) to furan (IV) gives access to benzo[c]chromene derivatives (V).

Polyfluorinated di-and triarylpyrazolines were synthesized by the reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine, respectively. Reactions of benzyl-idenepolyfluoroacetophenones with phenylhydrazine resulted in the mixtures of isomeric 1,5-diphenyl-3-polyfluoroaryl-and 1,3-diphenyl-5-polyfluoroarylpyrazolines. Fluorescence properties of the synthesized triarylpyrazolines were studied.

Vilsmeier—Haack formylation of methyl lambertianate results in its 16-formyl derivative as the predominant product, which readily enters the intramolecular reaction of photochemical [2+2]-cycloaddition in the absence of a sensitizer.

Condensation of 3-chloro-1,2,3-trimethyl-4-methylidenecyclobutene with 1,2-dimethyl-3,4-dimethylidenecyclobutene under the action of MgBr2 leading to spiro compounds was observed. The scheme of the process is discussed.

Reaction of α,β-unsaturated monoterpenic ketones-carvone, pinocarvone and 2-caren-4-one - with the sodium salt of diethylphosphite in diethylphosphite media results in regioselective addition to the conjugated carbon-carbon double bond and formation of the corresponding oxophosphonates.

1H and 13C NMR studies involving the 13C NMR deuterium perturbation method and ab initio calculations showed the interaction between 2,3-dimethyl-2-butene and the nitrosonium cation to form a dynamic π-complex.

Acetonation of rhaposerin is accompanied by migration of the O-acetyl group. Acetonation of 15-O-deacetylrhaposerin afforded isomeric O-isopropylidene derivatives containing five- and six-membered rings.

The first AlkNSNHetF sulfur diimide 6 (Alk=adamant-1-yl, HetF=2,3,5,6-tetrafluoropyrid-4-yl) was prepared by trapping of the corresponding alkylthiazylamide [AlkNSN]− 3 with pentafluoropyridine, followed by X-ray structural characterization. For 6, the Z,E configuration was found. From the reaction of 3 with octafluoronaphthalene, hexafluorinated naphthothiadiazole 7 was isolated along with the parent AlkNH2.

The reactions of α-pentafluorophenylpyrylium salts with hydroxylamine in ethanol afford isoxazoline derivatives and/or pyridine N-oxides depending on the steric characteristics of the substituent in the second α position. The structure of 2-hydroxy-2-pentafluorophenyl-4-phenyl-2,3,5,6,7,8-hexahydroquinoline 1-oxide, which was synthesized by the reaction of 2-pentafluorophenyl-4-phenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate with NH2OH, was established by X-ray diffraction.

1-Bromo-and 1-iodo-6,14-endo-ethenodihydrothebaine-hydroquinones were obtained. The Heck reactions of these halides with various olefins were studied.

The oxidation of N-acetyl-and N-benzoylanabasine with the tert-butyl hydroperoxide (TBHP)— MoCl5 system or MCPBA proceeds selectively at the nitrogen atom of the pyridine ring. The oxidation of N-methylanabasine under similar conditions gives a mixture of stereo-isomeric N-oxides at the piperidine nitrogen atom, their ratio depending on the reagent used. The oxidation of anabasine by TBHP— MoCl5 or MCPBA is accompanied by dehydrogenation and results in anabaseine N-oxide. The reactions of anabasine and anabaseine pyridine N-oxides with acetic anhydride were investigated. The substituted 1H-3-pyridin-2-ones were prepared.

Diels-Alder reaction of thebaine with maleimides is structurally specific and yields [7,8,3′,4′ ]-succinimido-endo-ethenotetrahydrothebaines containing N′-alkyl, cycloalkyl, aralkyl or aryl substituents. N′-[1(S)-hydroxymethyl-2-methylpropyl]-succinimido-6,14-endo-ethenotetrahydrothebaine formed in reaction of S-valinol with (7α,8α)-anhydrido-6,14-endo-ethenotetrahydrothebaine. The reduction of the adducts by LiAlH4 afforded N′-substituted 7,8-pyrrolidino-endo-ethenotetrahydrothebaines. The reduction of fused succinimides by NaBH4 resulted in the corresponding 2′α-hydroxylactam derivatives. O-Demethylation of the tetrahydrothebaine pyrrolidine derivatives effected by BBr3 afforded compounds of the tetrahydrooripavine series. The O-demethylation of tetrahydrothebaine succinimide derivatives gave rise to the corresponding 6-demethyl-endo-ethenotetrahydrooripavines. Alkylation conditions were found for N′-(4-hydroxyphenethyl)-substituted tetrahydrothebaine succinimide derivatives.

Photoanlogues of the initiation substrates of the RNA polymerase II, N3ArNH(CH2)(n)NHpppA where N3Ar is 5-azido-2-nitrobenzoyl group (n = 2 or 4) were synthesized, allowing the preparation of photoreactive oligonucleotides in situ by RNA polymerase II for application as photolabels. Photolysis of p-nitro-substituted aromatic azide in aqueous medium was investigated. Using the azoxy-coupling reaction it was possible to determine whether a nitrene or p-nitrophenyl hydroxylamine azoxy compound is the trappable intermediate that is generated at ambient temperature in aqueous solution.

Oxidation of (+)-sabinol, (1S,3R,5S)-1-isopropyl-4-methylidenebicyclo[3.1.0]hexan-3-ol, by active MnO2 afforded not the expected sabinone but only its [4+2]-cyclodimer. The molecular structure of the latter was established by X-ray diffraction analysis. The 1H and 13C NMR spectra of this cyclodimer were interpreted using 2D NMR spectroscopy.

The reactions of the natural flavonoids tectochrysin and pinostrobin with chlorine in methanol afforded for the first time their 6,8-dichloro derivatives. Under the reaction conditions, dichloropinostrobin was transformed further into a tetrachloromethoxy derivative. The molecular structure of the latter was established by X-ray diffraction analysis.

The stereoselective synthesis of two phosphorus-containing derivatives of the known guaianolide arglabin was carried out for the first time. The molecular structures of these products were established based on the spectroscopic data and the results of X-ray diffraction analysis of one of these compounds.

2,2'-Quinocyanines with long alkyl substituents on one or both nitrogen atoms have been synthesized. 1H NMR spectroscopy has been used to study the processes occurring during the alkylation of the starting quinoline bases.

The reaction of grossmisin (8α-hydroxyachillin,1) with chlorine in benzene afforded a mixture of products. The less polar product readily crystallized after chromatography. According to the X-ray diffraction data, this product has the structure of 1α,10β-dichloro-1,10-dihydrogrossmisin. The second chloro derivative of grossmisin,viz., 8β-chloroachillin, was prepared in good yield by the reaction of lactone1 with PCl5 in CHCl3 in the presence of Py.

The reaction of sesquiterpene lactone achillin with chlorine in methanol afforded four products,viz., two monochlorides and two dichlorides. One of these monochlorides is an intermediate in the formation of both dichlorides. The structures of the reaction products were established by two-dimensional NMR spectroscopy. The structure of one of the products was also established by X-ray diffraction analysis.