S. A. Torosyan

Disaccharide blocks for analogs of OSW-1

The acetalization of phenyl 1-thio-α-L-arabinopyranoside with 2,3-butanedione in the medium of MeOH-CH(OMe)3-CSA proceeded with the prevailing formation of the corresponding 3,4-bisacetal that further was converted in compounds, which were regio- and stereoisomers of disaccharide block of OSW-1.

New monomers for fullerene-containing polymers

By reaction of 2-(acryloyloxyethyl) and (undecen-10-en-1-yl) methylmalonates with fullerene C60 in the system toluene-CBr4-DBU, and also by reaction of 2-(2,2-dichloroacetoxy)ethyl acrylate with C60 in the system toluene-DBU the corresponding products of fullerene monocyclopropanation were synthesized.

Esters of dichloroacetic acid in the synthesis of fullerene C60 functionalized methane derivatives

X C It is well known that carbanions generated in situ from α-halomalonic esters cleanly react with fullerene С60 giving cyclopropane derivatives. This is a general approach that has been performed on versatile derivatives of malonic esters [1–4], Meldrum’s acid [5], and the other СН-acids [6]. The indispensable condition of the reaction to proceed is the possibility to generate from the reagent carbanion А possessing a halomethine function that adds to the electron-defi cient double bond of С60 providing the secondary carbanion B which via the intramolecular cyclization gives cyclopropanes C (Scheme 1). In this study we tested allyl dichloroacetate (I) as a new cyclopropanation agent for С60. As seen from the structure, the methane proton of compound I is strongly activated, it should be easily converted into a carbanion, and for the intramolecular cyclization the presence is feasible of a good leaving group (Cl–). In total this reaction rout should provide cyclopropanes D. The experimental test showed that in the reaction of about equimolar

UV spectroscopy of monosubstituted derivatives of 1,2-dihydro-C60-fullerenes

UV spectroscopy is used to determine the molar absorption coefficients of C60 fullerene and monosubstituted 1,2-dihydro-C60-fullerenes in different solvents. It is found that the extinction coefficient of C60 at 330 nm (the main absorption band most frequently used for qualitative and quantitative determination of the C60 content) is independent of the nature of the solvent and is ∼54400 M−1·cm−1. The molar absorption coefficients of a series of monosubstituted 1,2-dihydro-C60-fullerenes are practically independent of the chemical structure and the length of the substituent and are 35700 M−1·cm−1 (λ ∼ 328 nm) and 115250 M−1·cm−1 (λ ∼ 257 nm). It is shown that the substitution in fullerene proceeds via the double 6,6 bond, as evidenced by the absorption band at 424 nm in the spectra of these compounds, which is characteristic of monosubstituted methanofullerenes.

Bis(Allyloxycarbonyl)methano derivatives of fullerene C60

Mono-, bis-, tris-, tetrakis-, and hexakis-substituted cyclopropanation products of fullerene C60 with diallyl malonate were synthesized according to Bingel-Hirsch. Except for the monocyclopropanation product, all other adducts were isolated as mixtures of regioisomers.

Reaction of 5-Allyl-2,3,5-trichloro-4,4-dimethoxycyclopent-2-en-1-one with amino acids

Abstract5-Allyl-2,3,5-trichloro-4,4-dimethoxycyclopent-2-en-1-one reacts with L-proline and L-methionine methyl esters to give diastereoisomeric mixtures of the corresponding chlorine replacement products at C3.

Ring-opening metathesis polymerization (ROMP) of fullerene-containing monomers in the presence of a first-generation Grubbs catalyst

New norbornene-type monomers containing covalently bound C60 fullerene have been obtained. In the presence of the 1st generation Grubbs catalyst [(PCy3)2Cl2RuCHPh] (Cy is cyclohexyl), these monomers smoothly undergo homopolymerization and copolymerization with parent fullerene-free monomers. The homopolymers are insoluble in common organic solvents, while the copolymers obtained at different molar ratios to their fullerene-free analogues are very soluble in organic solvents and can be suitable for the preparation of thin films.

Polynorbornenes modified by methanofullerene and 1-phenyltetrazol-5-ylsulfanylmethyl blocks

Ring-opening metathesis polymerization of norbornene monomers linked to fullerene and 1-phenyltetrazol-5-ylsulfanylmethyl fragments at a molar ratio of 1: 1 afforded a copolymer containing 30% of fullerene units and soluble in organic solvents.

UV spectroscopy of methanofullerene derivatives with different degrees of substitution

Compounds from the series of methanofullerenes with different degrees of functionalization were studied by UV spectroscopy. As the number of substituents increased, a hypsochromic shift of the characteristic absorption bands took place and the optical density of the solutions of the compounds at characteristic maxima decreased. A similar dependence was also noted for the ratio of the optical densities of the 258 and 329 nm bands typical for fullerene (A258/A329). An exponential dependence of the molar absorption coefficients of metanofullerenes on the degree of functionalization of the fullerene nucleus was found.

Synthesis of chloramphenicol conjugate with fullerene C60

Main efforts in the design and synthesis of organofunctionalized derivatives of fullerene C60 for medical purposes are addressed to create water-soluble compounds [1–3]. Among them, antiviral [4], anticarcinogenic [5], and antibacterial agents [6], radical scavengers [7], etc. [8], have been found. An important research line in this field is the synthesis of coordination and covalently bound C60 compounds with biologically active molecules used in medical practice. For example, the anticancer activity of the C60‒doxorubicin complex is higher by a factor of 1.5‒2 than the activity of doxorubicin taken alone [9]; analogous effect is observed for the complex C60‒dexamethasone [10]. As a rule, the complexation improves transport and prolongs action of drugs, and in some cases synergistic effect is achieved. A different situation is observed with covalent bonding of C60 with drugs. Zakharian et al. [11] proposed to use C60 conjugate with paclitaxel (Taxol) for lipophilic chemotherapy of lung cancer. It was noted that C60 is an ideal partner for the lipophilization of drugs via conjugation. Conjugates of C60 with antibiotics [12] have been patented, and C60 conjugates with isoniazid [13], dehydroabietylamine [14], amino acids [15], and other biologically active molecules have been synthesized. In most cases, the biological activity profile was retained; however, it may change since a radically new molecular architecture is concerned.