Valeriy I. Smirnov

Fluorescence quenching and laser photolysis of dipyrrolylbenzenes in the presence of chloromethanes

Fluorescence quenching of 1,4-bis(1H-pyrrol-1-yl)benzene, 1-(1H-pyrrol-2-yl)-1-(1-vinyl-1H-pyrrol-1-yl)benzene, and 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene with chloromethanes (methylene chloride, chloroform, and carbon tetrachloride) in solvents with different polarities follows electron-transfer mechanism. The occurrence of an electron-transfer step is confirmed by formation of short-lived pyrrolylbenzene radical cations. An exception is quenching of fluorescence of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene in n-hexane in the presence of CCl4 and CHCl3 and in pure CCl4. In this case, neutral 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene·-Cl radical is formed via recombination of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene radical cation and chloride anion. A relation was found between the nature of the short-lived species detected by laser photolysis and stable product obtained by stationary photolysis.

Superbase-Assisted Addition of Phosphine to 1-Methoxy-4-vinylbenzene: Toward a Rare Family of Organic Phosphines

Abstract Phosphine reacts with 1-methoxy-4-vinylbenzene in the superbase suspension KOH-dimethylsulfoxide (70–100 °C, atmospheric pressure) to form regiospecifically anti-Markovnikov adducts, bis[2-(4-methoxyphenyl)ethyl]phosphine (1) and tris[2-(4-methoxyphenyl)ethyl]phosphine (2), representatives of rare arylalkylphosphines. The conditions for the selective preparation of phosphines 1 or 2 in 67% and 80% yields, respectively, have been elaborated. The phosphines have been oxidized with aqueous solution of H2O2, elemental sulfur, or selenium to afford the corresponding phosphine chalcogenides in good yields (95–99%). GRAPHICAL ABSTRACT

Novel quinine, lupinine, and anabasine derivatives containing dithiophosphinate groups

A three-component, atom-economic reaction between natural quinine, lupinine, or anabasine, secondary phosphines, and elemental sulfur occurs under mild conditions to yield previously unknown optically active dithiophosphinates.

Stereoselective Synthesis of N -[( Z )-2-Cyano-1-Phenylethenyl]Benzimidazole-2-Carbothioamides by a Three-Component Reaction of 1-Substituted Benzimidazoles, Phenylcyanoacetylene, and Isothiocyanates

A new method has been developed for the synthesis of benzimidazole carbothioamides, which have potential pharmacological activity, by a three-component reaction of 1-substituted benzimidazoles, phenylcyanoacetylene, and methyl, allyl, or phenyl isothiocyanates. The reaction of these components proceeds under mild conditions in acetonitrile at 50-55°C for 12-20 h and stereoselectively leads to N-[(Z)-2-cyano-1-phenylethenyl]benzimidazole-2-carbothioamides in 43-82% yield.

Influence of N-metylation effect on the dissolution enthalpy of glycoluryl in water

Earlier [3, 4] we have shown that 2,4,6,8-tetramethyl-bis-carbamide (TMbCA), or mebicar, on dissolving in water shows small endothermic effect ( solH 2 3.67 kJ mol ) despite the presence in its molecule of the same number of CH3 groups as in hydrophobically hydrating tetramethylcarbamide (TMCA: solH 2 24.53 kJ mol 1 [5]). Accounting for this observation we suggest that the problem how the process of N-methylation affects enthalpy characteristics of dissolving in water protonated (that is, unsubstituted) glycoluril of bis-carbamide series (see the scheme) is also significant. The glycoluril bis-carbamide (bCA) is much more hydrophilic than TMbCA but is scarcely dissolving in water (5 10 3 mol per 1000 g of H2O at 298.15 K, or less).

Unexpected assembly of substituted pyrrole from 3-trimethylsilylprop-2-ynal and ethyl 3-anilinobut-2-enoate

Pyrroles are important heterocyclic compounds that are widely used in high technologies [1]. Pyrrole ring is a base fragment of many biologically significant molecular structures [2, 3]; the importance of pyrrole derivatives in pharmacology is also obvious [4]. Therefore, it is not surprising that huge attention has been paid to the development of methods for the synthesis of various pyrrole compounds and studying their chemical, physical, and biological properties [5–9]. Acetylene and its derivatives were widely used to build up pyrrole systems. Various pyrroles were synthesized by one-pot reactions of ketoximes with acetylene (Trofimov reaction) [10]. Efficient synthesis of functionalized pyrroles from acetylenic compounds in the presence of transition metal catalysts has been reported [11, 12]. Acetylenedicarboxylic acid and its esters [13, 14], α-acetylenic ketones [15, 16], terminal aryland alkylacetylenes [17], electron-deficient propargylamines [18], propargyl vinyl ethers [19, 20], propargyl enamines [21], and alkynylalkenals [22] were used as initial acetylenic compounds. However, almost no syntheses of pyrroles from α-acetylenic aldehydes were reported. Dunford et al. [23] were the only to describe successive transformation of propynals into β-hydroxyhomopropargylic sulfonamides and their cyclization to pyrroles, catalyzed by Cu(OAc)2. We have recently demonstrated the potential of propynals in the synthesis of heterocyclic compounds, including those containing a side-chain triple bond [24, 25]. We now report a new three-component reaction of 3-trimethylsilylprop-2-ynal (1) with ethyl acetoacetate (2) and ethyl 3-anilinobut-2-enoate (3), leading to the formation of previously unknown ethyl 5-[2-(ethoxycarbonyl)-3-oxo-1-(trimethylsilyl)butyl]2-methyl-N-phenyl-1H-pyrrole-3-carboxylate (4) in 42% yield. The reaction was carried out by heating the reactants in boiling benzene for 3 h in the presence of 15 mol % of ZnCl2. It should be specially noted that the pyrrole ring of 4 is also assembled in the absence of ester 2 since ethyl 3-anilinobut-2-enoate (3) under the given conditions (by the action of Lewis acid) partially decomposes into 2 and aniline. The reaction was also accompanied by formation of 13% of ethyl 2-acetyl-5-(trimethylsilyl)pent-2-en-4-ynoate as a result of Knoevenagel condensation of 1 and 2. It is also important that final product 4 contains a trimethylsilyl group on sp-carbon atom. In all cascade heterocyclizations involving trimethylsilylpropynal 1 the Me3Si group remained attached exclusively to sp-carbon atom [25]. A probable reason is that the reaction was carried out in nonpolar benzene.

New synthesis of poly(phenothiazine-3,7-diyl)

Development of the chemistry of phenothiazine is stimulated by therapeutic effect of some its derivatives in the treatment of nervous system disorders [1]. At present, researchers’ interest is focused on the synthesis and properties of macromolecular systems based on phenothiazine. It is known that polyphenothiazine derivatives exhibit unique electrical and photoelectric properties [2]. Poly(phenothiazine-3,7-diyl) compounds are commonly prepared by the Grignard and Heck reactions in the presence of nickel and palladium catalysts [3, 4]. Unsubstituted poly(phenothiazine-3,7-diyl) was synthesized by phase-transfer oxidative polymerization using ammonium peroxosulfate as oxidant [5]. We were the first to reveal that photolysis of fused (130°C) 2-iodo-1-(10H-phenothiazin-10-yl)ethanone (I) in the absence of a catalyst yields 66% of iodinedoped poly(phenothiazine-3,7-diyl) (II). The reaction involves cleavage of the N–C, C–C, and C–I bonds and is accompanied by liberation of carbon(II) oxide and ethylene. The IR spectrum of the gas mixture contained absorption bands at 1640 and 3100 cm typical of stretching vibrations of the C=C and C–H bonds in ethylene molecule and a band at 2100 cm belonging to carbon(II) oxide. Presumably, migration of the radical center in the initially formed nitrogencentered phenothiazine radical to the 3(7)-position is followed by combination with formation of dimeric structures, which promotes 1,5-prototropic shifts. Further growth of the polymer chain is favored by abstraction of hydrogen atoms from C (C) by iodine radical.

Synthesis of 1-organyl-1-(trimethylsiloxy)-2-(dimethylamino)ethenes and new hypervalent silicon compounds based thereon

Abstract1-Organyl-1-(trimethylsiloxy)-2-(dimethylamino)ethenes were synthesized for the first time, and their reactions with trichloro(methyl)silane and trifluoro(phenyl)silane afforded silicon bis-chelates, methylbis-[2-(dimethylamino)-1-(organyl)ethenolato-N,O]siliconium chlorides and bis[1-(dimethylamino)-3,3-dimethylbut-1-en-2-olato-N,O]fluoro(phenyl)silicon(IV), respectively.

Synthesis of poly(2,2′,3,3′-indole)

New approaches to the synthesis of poly(2,2′,3,3′-indole) were developed based on the photochemical dehydropolycondensation of indole in the presence of iodine and the photochemical polycondensation of 1-(1H-indol-3-yl)-2-iodo-1-ethanone in the absence of catalyst and solvent. A suggested mechanism for the formation of the oligomeric chain in these reactions includes the intermediate formation of 3,3′-diindole with subsequent polycondensation via elimination of hydrogen atoms at position 2 of the dimer pyrrole fragment.

Quantum-chemical study of intramolecular photocyclization in bis(thioxopropenyl) sulfide systems

Principal possibility of formation of trithiatetracyclononane structures via intramolecular rearrangements in bis(thioxopropenyl) sulfide systems, involving the lowest triplet state, was studied by the DFT(B3LYP) quantum-chemical molecular modeling analysis.