A. V. Kletskov

Isoxazol-3-yl(Isothiazol-3-yl)-1,2,4-Triazoles, Tetrazoles, and -1,3,4-Oxadiazoles: Synthesis, Palladium Complexes, and Catalytic Applications

We used 5-arylisoxazole-3-carbonitriles and 4-R-5-chloroisothiazole-3-carbonitriles to prepare the corresponding (5-arylisoxazol-3-yl)- and (4-R-5-chloroisothiazol-3-yl)-1,2,4-triazoles, -tetrazoles, and -1,3,4-oxadiazoles. The obtained bis-heterocycles along with some of the intermediate monocyclic azoles formed palladium complexes that were highly active Suzuki reaction catalysts in aqueous and aqueous-alcohol media.

Functionally substituted isoxazoles and isothiazoles: Synthesis, palladium(II) complexes and their catalytic activity

Functionally substituted 5-(p-tolyl)isoxazoles and 4,5-dichloroisothiazoles, whose molecules contain azomethine, amino, carboxyl, and ester moieties in various combinations in the aromatic ring in the position 3 of heterocycle, were synthesized. Synthesis of complexes of Pd(II) with carboxyl derivative of 1,2-azoles was performed. They show high catalytic activity in the Suzuki reaction in aqueous media.

Synthesis of functionally substituted isoxazole and isothiazole derivatives

Acylation of benzene and toluene with 5-phenyl- and 5-(p-tolyl)isoxazole-3-carbonyl chlorides gave 5-phenyl(or p-tolyl)isoxazol-3-yl phenyl(or p-tolyl)ketones which were reduced to the corresponding alcohols with sodium tetrahydridoborate in propan-2-ol. Selective reduction of the carboxy group in 4,5-dichloroisothiazole-3-carboxylic acid was achieved by the action of BH3, and the aldehyde group in 4-formyl-2-methoxyphenyl 5-arylisoxazole-3-carboxylates and 4,5-dichloroisothiazole-3-carboxylates was reduced to hydroxymethyl group with sodium triacetoxyhydridoborate in benzene. Acylation of the resulting hydroxymethyl derivatives with 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides afforded the corresponding esters containing two azole fragments in their molecules.

The Synthesis of Isoxazolyl- and Isothiazolylcarbamides Exhibiting Antitumor Activity

Accessible 5-phenyl(p-tolyl)isoxazol-3-carboxylic, 4,5-dichlorothiazol-3-carboxylic and 5-(benzylsulfanyl)-4-chlorothiazol-3-carboxylic acids were converted via a series of cascade transformations into the corresponding (1,2-azolyl)-3-carbonyl azides whose reaction with slightly basic aryl(heteryl)amines led to generation of 1-(1,2-azolyl)-3-aryl(heteryl)carbamides. To obtain isoxazolyl(isothiazolyl)carbamides containing the residues of highly basic amines, (1,2-azolyl)-3-carbonyl azides were preliminary transformed into aryl (1,2-azol-3-yl)carbamates by the action of phenol or 4-fluorophenol. Carbamates then were introduced into reaction with aliphatic or heterocyclic amines. Some of the obtained compounds and their precursors show high antitumor activity and are capable to increase the effect of cytostatic drugs applied in the medical practice.

Synthesis of esters of metallocene alcohols and 4,5-dichloroisothiazol-3-carboxylic and 5-arylisoxazole-3-carboxylic acids

Acylation of alkyl- and 1,1′-dialkylferrocene alcohols and diols as well as (3,4,4-trichlorobut-3-ene-1-ol-1-yl)-4,5-cymantrene with dichloroisothiazole- and 5-arylisoxazole-3-carbonyl chlorides has afforded esters containing 1,2-azoles fragments. Some of the obtained compounds have exhibited potentiating action in the binary mixtures with insecticides.

The influence of heterocyclic compound-PAMAM dendrimer complexes on evoked electrical responses in slices of hypoxic brain tissue

We used complexes between a fourth generation polyamidoamine (PAMAM) dendrimer and one of two heterocyclic compounds — 1-(6-hydroxyhexyl)-3-(5-phenyl-isoxazole-3-yl)-urea or 5-phenyl-isoxazole-3-carboxylic acid — to reduce oxygen consumption in transverse slices of the hippocampus taken from 4-week old male rats. In vitro electrophysiological experiments revealed that the inhibitory effect of the hypoxic state on the evoked responses was enhanced in the presence of the complexes. The data were analyzed in terms of the potential antitumor effects of these complexes.

Synthesis of alkyl (4,5-Dichloroisothiazol-3-yl) ketones and some of their derivatives

Reactions of 4,5-dichloroisothiazol-3-ylcarbonitrile with methylmagnesium iodide and ethylmagnesium bromide afforded the corresponding alkyl (4,5-dichloroisothiazol-3-yl) ketones. The reaction of (4,5-dichloroisothiazol-3-yl) methyl ketone with morpholine and piperidine provided 5-morpholino-(piperidino)-substituted derivatives, by the action of sodium borohydride in 2-propanol the keto group was reduced to alcoholic hydroxy group. The bromination of (4,5-dichloroisothiazol-3-yl) methyl ketone with elemental bromine gave bromomethyl (4,5-dichloroisothiazol-3-yl) ketone, whose reaction with thiourea resulted in 2-amino-4-(4,5-dichloroisothiazol-3-yl)thiazole.

Catalytic synthesis of 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) and 3,3,6,6-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones

Condensation of substituted benzaldehydes of vanillin series with dimedone in methanol solution in the presence of catalytic quantities of triethylamine afforded 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones. By catalytic cyclization of the latter in boiling benzene in the presence of sulfo cation exchanger FIBAN K-1 as catalyst 3,3,6,6-trimethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones were synthesized.

Esters of benzoic, 5-arylisoxazole-3-carboxylic and 4,5-dichloroisothiazole-3-carboxylic acids

The method of synthesis was developed of esters of benzoic, 2-chlorobenzoic, 5-phenylisoxazole-3-carboxylic, 5-tolylisoxazole-3-carboxylic, and 4,5-dichloroisothiazole-3-carboxylic acids with some aliphatic and substituted aromatic alcohols. The latter were obtained by reduction of aldehydes used in perfumery.

Synthesis of Azaheterocyclic Cymantrene Derivatives

The reduction of acetylcymantrene with sodium tetrahydridoborate gave cymantrenylethanol which was acylated with 4,5-dichloroisothiazole- and 5-(4-methylphenyl)isoxazole-3-carbonyl chlorides to obtain esters containing a 1,2-thia(oxa)zole fragment. The condensation of acetylcymantrene with 5-arylisoxazole-3- carbaldehydes, (5-arylisoxazol-3-yl)methoxybenzaldehydes (Ar = Ph, 4-Tol), and 4,5-dichloroisothiazole-3- carbaldehyde afforded the corresponding (E)-3-(azol-3-yl)-1-cymantrenylprop-2-en-1-ones. The resulting α,β- unsaturated ketones reacted with semicarbazide hydrochloride and thiosemicarbazide to produce substituted 4,5-dihydro-1H-pyrazole-1-carboxamides and -1-carbothioamides, and their reaction with hydroxylamine hydrochloride led to the formation of 4,5-dihydroisoxazoles containing cymantrene and 1,2-azole fragments. Heterocyclization of azolylcymantrenylpropenones with guanidine gave 2-aminopyrimidine derivatives, and dihydropyrimidine-2-thiones were obtained by their reaction with thiourea.