E. M. Gibadullina

Amphiphilic O-functionalized calix[4]resocinarenes with tunable structural behavior

Novel amphiphilic calix[4]resorcinarenes oxyethylated at the upper rim and alkylated at the lower rim (CR–CnH2n+1, here n is the number of carbon atoms in the alkyl substituent; n = 2,5,7,8,9,11) were synthesized, and their association behavior in water-organic solvents was explored. Surface properties and the association behavior of CRs were shown to be strongly controlled by their structure and the nature of the co-solvent. Solely CR–C5H11 demonstrates surface activity in the mixed water–DMF and water–DMSO solutions, while no surface activity occurs in the water–THF mixture. The DLS measurements revealed a very low concentration threshold of the aggregation (around 0.01 mM) for the CR series including surface inactive compounds. In water–DMF and water–DMSO solutions the CRs of low hydrophobicity were shown to associate through an open model with the formation of large aggregates of 300–400 nm, while more hydrophobic CRs can associate through a closed model and form rather small micelle-like aggregates of 10 to 20 nm.

Synthesis of new α-aminophosphonates containing sterically hindered phenol fragments based on the reaction of 3,5-di(tert-butyl)-4-oxo-2,5-cyclohexadienylidenemethylphosphonates with aliphatic amines

A reaction of aliphatic amines (n-butylamine, sec-butylamine, tert-butylamine, dodecylamine, 1,12-diaminododecane) with α-phosphorylated methylenequinones (dimethyl {[3,5-di-(tert-butyl)-4-oxo-2,5-cyclohexadienylidene]methyl}phosphonate and diphenyl {[3,5-di(tertbutyl)-4-oxo-2,5-cyclohexadienylidene]methyl}phosphonate)) to form 1,6-nucleophilic addition products was studied. This approach was used to obtain a-aminophosphonates containing sterically hindered phenol fragments in high yields.

Synthesis, Genotoxicity and UV-protective Activity of New Benzofuroxans Substituted by Aromatic Amines

The synthesis of new organic compounds possessing properties, which can be used for biological or pharmaceutical purpose, is very challenging and is a current trend in heterocyclic chemistry. So benzofuroxans are of great interest from a medical and combinatory chemistry point of view, being effective biologically active compounds. They are easily available, easily tuned and functionalized allowing the creation of databases in which a chemist can find proper informations to prepare the structurally appropriate compound with the requested selective effect. In this work, heterocyclic compounds are prepared on the basis of the interaction of 4,6-dichloro-5-nitrobenzofuroxan with aromatic amines and diamines. Their ability to suppress and prevent genotoxic effects of UV-radiation in the wavelength range between 300-400 nm has been studied. It has been shown that these compounds are able to protect bacterial cells from destructive effects of the UV-radiation. Comparing the results obtained for various benzofuroxans to those obtained for the natural antioxidant  - tocopherol (vitamin E) and for the synthetic antioxidant trolox, which are references in this domain, we have shown that some benzofuroxans quantitatively exhibit a similar protective effect, and that compounds prepared from the reaction between 4,6-dichloro-5-nitrobenzofuroxan and ethylenedianiline possess potent protective potential.

α-Phosphorylated 2,6-di-tert-butyl-4-methylidene-2,5-cyclohexadienones in the reactions with meta-phenylenediamine

Sterically hindered 2,6 dialkylphenols, being bio mimetics of natural antioxidant  tocopherol (vitamin E), belong to a known class of widely used phenol antioxi dants.1 Development of polyfunctional antioxidants2,3 is one of the main trends in the last decades. Phosphorus containing ionol derivatives are efficient antioxidants, since the presence of several reaction centers in the molecule provides inhibition of oxidation processes following vari ous mechanisms: sterically hindered phenol fragment ef fects antiradical protection, whereas phosphoryl fragment is responsible for the inhibition in the reactions of other than radical decomposition of hydroperoxides.4,5 Reac tive and at the same time stable  phosphorylated 2,6 di tert butyl 4 methylidene 2,5 cyclohexadienones are con venient reagents for the preparation of new functionally substituted organophosphorus derivatives.6,7 In the present work, we studied synthetic possibilities of phosphorylated 2,6 di tert butyl 4 methylidene 2,5 cyclohexadienones, viz., dimethyl [(3,5 di tert butyl 4 oxo 2,5 cyclohexadi enylidene)methyl]phosphonate (1a) and diphenyl [(3,5 di tert butyl 4 oxo 2,5 cyclohexadienylidene)methyl] phosphonate (1b) in the reactions with m phenylene diamine. The reaction of phosphorylated methylidenequinones with proton donating nucleophilic agents is known to fol low the scheme of nucleophilic 1,6 addition.8,9 We found that  phosphorylated methylidenequinones 1a,b readily react with m phenylenediamine following earlier unknown pathway of electrophilic substitution in the aromatic ring with the formation of 1 : 1 products 2a,b in high yields (Scheme 1), rather than nucleophilic 1,6 addition at the free amino groups. The structure of compounds 2a,b was confirmed by 1H and 31P NMR and IR spectroscopy, their composition by mass spectrometry (MALDI TOF) and elemental analysis. To sum up, m phenylenediamine in the reactions with  phosphorylated 2,6 di tert butyl 4 methylidene 2,5 cyclohexadienones acts as a C nucleophile with the for mation of the products of electrophilic substitution.

Synthesis and binding ability of mono- and tetrasubstituted aminophosphonate Zn-tetraarylporphyrins towards N- and O-containing organic substrates

The 1,6-addition of mono- and tetra-amino 5,10,15,20-tetraphenylporphyrins with dimethyl-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidenemethyl)phosphonate leads to the corresponding mono- and tetrasubstituted aminophosphonate porphyrin derivatives. The binding ability of their Zn(II)-complexes towards 1,4-diazabicyclo[2,2,2]octane, imidazole, 4-(1H-imidazole-1-yl)benzyl alcohol and 4-(1H-imidazole-1-ylmethyl)benzyl alcohol in toluene was investigated by spectrophotometric and 1H NMR titration. It has been determined that the monosubstituted Zn-tetraarylporphyrin is involved in a two-point selective binding of 4-(1H-imidazole-1-ylmethyl)benzyl alcohol. Taking into account the fact that this binding is accompanied by a clear and easily identifiable response in the UV–vis spectra of the reaction mixture, this metalloporphyrin could be considered as a molecular optical sensing device for selected bidentate N- and O-containing substrates.

Phosphorylation of Oxyethylated Calix[4]resorcinols with Phosphorous Acid Amides

The reaction of octa-2-hydroxyethylated calix[4]resorcinols with phosphorous acid amides and the subsequent thionylation by elemental sulfur afforded hydrolytically stable oxyethyl calix[4]resorcinols containing eight thiophosphoryl fragments.

Reaction of phosphorylated 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dien-1-ones with 2,2′-[1,3-phenylenebis(oxy)]-di(ethan-1-amine)

Dialkyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]phosphonates reacted with 2,2′-[1,3-phenylenebis(oxy)]di(ethan-1-amine) dihydrochloride at a ratio of 2: 1 in dioxane in the presence of potassium carbonate to give previously unknown tetraalkyl {1,3-phenylenebis[oxyethane-2,1-diylazanediyl-(3,5-di-tert-butyl-4-hydroxyphenylmethylene)]}bisphosphonates in high yields.

Supramolecular systems based on polyethyleneimines and octa-2-hydroxyethylated calix[4]resorcinarenes. Aggregation and catalytic activity

The aggregation of octa-2-hydroxyethylated calix[4]resorcines (CR) with different alkyl chain length (R = Et, n-C5H11, n-C11H23), hydrophobically modified polyethyleneimine (HPEI) and their mixed systems was investigated by the tensiometry and dynamic light scattering in water and water-organic solvents at different temperatures. The critical aggregation concentration (CAC) and the size of aggregates were determined. It was established that the temperature affects significantly the surface and aggregation properties of the CR. The hydrolysis of 4-nitrophenyl-О-butylchloromethyl phosphonate was investigated in the presence of CR, HPEI, and their mixed systems by spectrophotometry. The parameters of the reaction (rate constant in the micellar phase, binding constant of the substrate with aggregates, and CAC) testify that the catalytic activity of the HPEI system in the presence of СR with undecyl radicals is the highest.

Synthesis and dimerization of dibutyl (3,5-di -tert -butyl-4-oxo-2,5-cyclohexadienylidenemethyl)phosphonate

While studing the synthesis and properties of phospho rylated methylenequinones,1—5 we have accessed dibutyl (3,5 di tert butyl 4 oxo 2,5 cyclohexadienylidenemeth yl)phosphonate (1) by oxidation of dibutyl (3,5 di tert butyl 4 hydroxybenzyl)phosphonate (2) with alkaline po tassium ferrihexacyanide (Scheme 1). The structure and composition of compound 1 were established based on the 1H, 31P NMR and IR spectro scopic data, mass spectrometric (MALDI) data, and ele mental analysis. We found that with time compound 1 undergoes dimerization leading to 1,2 bis(dibutoxyphos phoryl) 1,2 bis(3,5 di tert butyl 4 hydroxyphenyl)ethane (3). The process reached completion within 10 days, which was indicated by the disappearance in the 31P NMR spec trum of the signal for the starting compound 1 (P 15.0) and the presence of the only singlet for the dimerization product 3 (P 27.5). The structure and composition of compound 3 were confirmed by the 1H, 31P NMR and IR spectroscopic data, mass spectrometric (MALDI) data, elemental analysis, and X ray diffraction studies (Fig. 1). It should be noted that in the solution in benzene, methylenequinone 1 did not undergo visible changes over prolonged period of time.

Reactions of [(3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dien- 1-ylidene)methyl]phosphonates with Phenols

Dialkyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]phosphonates reacted with phenol and benzenediols in the presence of trifluoromethanesulfonic acid to give products of electrophilic substitution in the benzene ring, the corresponding diarylmethylphosphonates or [phenylenebis(arylmethylene)]- diphosphonates. The reaction of diphenyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]phosphonate with 2-methylbenzene-1,3-diol at a ratio of 1: 1 afforded 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-6-hydroxy-7-methyl-2-phenoxy-2,3-dihydro-1,2λ5-benzoxaphosphol-6-one.