Catalytic C-phenylation of methyl acrylate with tetraphenylantimony(v) halides and carboxylates

Catalytic C-phenylation of methyl acrylate to methyl cinnamate with the Ph₄SbX complexes (X = F, Cl, Br, OH, OAc, O₂CEt) in the presence of the palladium compounds PdCl₂, Pd(OAc)₂, Pd₂(dba)₃, Pd(Ph₃P)₂Cl₂, and Pd(dppf)Cl₂ (dba is dibenzylideneacetone and dppf is bis(diphenylphosphinoferrocene)) was studied in organic solvents (MeCN, THF, DMF, MeOH, and AcOH). The highest yield of methyl cinnamate (73% based on the starting organometallic compound) was obtained for the Ph₄SbCl—PdCl₂ (1 : 0.04) system in acetonitrile.     

New homo- and heteroleptic derivatives of trivalent ytterbium containing radical anion 1,4-diazadiene ligands. Synthesis, properties, and crystal structures of the complexes (C9H7)2Yb[2-MeC6H4NC(Me)C(Me)NC6H4Me-2] and [PhNC(Ph)C(Ph)NPh]3Yb

The interaction of the ytterbium bis(indenyl) complex (C₉H₇)₂Yb^II(THF)₂ (1) with the 1,4-diazabutadiene 2-MeC₆H₄N=C(Me)-C(Me)=NC₆H₄Me-2 (^MeDAD) is accompanied by the oxidation of the metal atom to the trivalent state and results in a paramagnetic compound of the metallocene type (C₉H₇)₂Yb^III(^MeDAD^−·) (3) containing the radical anion of 1,4-diazabutadiene. The structure of the complex 3 was determined by X-ray diffraction analysis. The reactions of the bis(indenyl) (1) and bis(fluorenyl) (C₁₃H₉)₂Yb^II(THF)₂ (2) derivatives of divalent ytterbium with the 1,4-diazabutadiene PhN=C(Ph)-C(Ph)=NPh (^PhDAD) (with the molar ratio of the reactants 1:2) proceed with a complete cleavage of the bonds Yb-C and the oxidation of the ytterbium atom to the trivalent state and result in a homoligand complex (^PhDAD^−·)₃Yb (6) containing three radical anion 1,4-diazadiene ligands. Complex 6 was also obtained by an exchange reaction of YbCl₃ with ^PhDAD^−·K⁺ (1: 3) in THF. Complex 6 was characterized by X-ray diffraction analysis.     

Synthesis of fluorescent coumarin triazolylglycosides

A series of coumarin triazolylglycosides were synthesized in good yields using copper-mediated 1,3-dipolar cycloaddition reactions of carbohydrate azides and 4-alkynyl-substituted coumarins. Several of the products show strong luminescence in the 490-560 nm region and are compatible with surface imaging applications.     

New calсium β-diketonate complexes: The monomeric complexes [Ca(PhCOCHCOCF3)2(15-crown-5)], [Ca(AdCOCHCOCF3)2(15-crown-5)] and the binuclear hydrated complex [{Ca(adtfa)(18-crown-6)(H2O)}{Ca(adtfa)3(H2O)}(EtOH)]. Synthesis, characterization and crystal structure

The preparation of the Ca-β-diketonate complexes with crown-ethers, [Ca(btfa)₂(15-crown-5)] (1), [Ca(adtfa)₂(15-crown-5)] (2), [Ca(adtfa)₂(15-crown-5)](C₆H₅CH₃)_0.5 (3) and [{Ca(adtfa)(18-crown-6)(H₂O)}{Ca(adtfa)₃(H₂O)}(EtOH)] (4) (btfa = 1,1,1-trifluoro-4-phenyl-butanedionato-2,4; adtfa = 1,1,1-trifluoro-4-(1-adamantyl)butanedionato-2,4; 15-crown-5 = 1,4,7,10,13-pentaoxacyclopentadecane; 18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane), is described. Complex 1 has been prepared from the reaction of metallic Ca with 2 eq. of Hbtfa and 1 eq. of 15-crown-5 in toluene; complex 2 has been prepared from the reaction of metallic Ca with 2 eq. of Hadtfa and 1 eq. of 15-crown-5 in ethanol. The solvated complex 3 was obtained by cooling of a toluene-hexane solution of 2. The hydrated complex 4 was prepared from the reaction of metallic Ca with 2 eq. of Hadtfa and 1 eq. of 18-crown-6, followed by addition of excess H₂O to the resulting reaction mixture. The all complexes were characterized by elemental analyses, IR-spectroscopy, NMR-spectroscopy, single-crystal X-ray diffraction methods, DSC and TGA. A single-crystal X-ray study of 1 and 3 has show that complexes 1 and 3 are monomeric and contain the calcium atom bonded with two β-diketonate ligands and one molecule of crown-ether. Complex 4, as shown by X-ray analyses, is an ion-paired solvated adduct, containing the cation {Ca(adtfa)(18-crown-6)(H₂O)}⁺ and the anion {Ca(adtfa)₃(H₂O)}⁻. The monomeric complexes 1-3 are volatile and thermally stable in the temperature range 100-260 °C. Complex 4 undergoes decomposition above 110 °C with consecutive loss of ethanol, H₂O, 18-crown-6 and some evaporization of 4.     

Oxidation of triphenylantimony with 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone or 3,4,6-triisopropyl-1,2-benzoquinone

According to the NMR spectroscopic data, the oxidation of triphenylantimony with 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone involves three steps. The first step affords the 2,4,10,12-tetraoxa-3,11-distibatricyclo[11.3.1.1^5,9]octadecatetraene derivative. The latter is rearranged into benzodioxastibolone derivatives followed by the rearrangement into 4,6,7-triisopropyl-2,2,2-triphenyl-1,3,2-benzodioxastibol-5-ol. The transformation of the latter depends on the presence of oxygen and the mode of its dosing. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1750–1757, September, 2007.     

Synthesis of 3′H-cyclopropa[1,9](C60-I h)[5,6]fullerenes from 2′-aryl-1′,1′-dimethyl-2′,5′-dihydro-1′H-pyrrolo[3′,4′:1,9]-(C60-I h)[5,6]fulleren-1-ium iodides

Russian Journal of Organic Chemistry - New 1′,1′-dimethyl-2′,5′-dihydro-1′H-pyrrolo[3′,4′:1,9](C60-I h)[5,6]fulleren-1-ium iodides containing different...     

Synthesis of hydrophilic and lipophilic 4-arylcoumarin phosphates

Novel hydrophilic and lipophilic prodrugs, sodium 4-arylcoumarin dialkylphosphates and 4-arylcoumarin dioleyl phosphates, were synthesized by phosphorylation of 4-arylcoumarins with dialkylphosphites.     

Antitumor liposomes bearing a prodrug of combretastatin A-4 and a tetrasaccharide ligand of selectins

Therapeutic liposomes with an average diameter of 100 nm based on natural phospholipids (phosphatidylcholine and phosphatidylinositol) containing palmitoyl or oleoyl derivatives of the antimitotic agent combretastatin A-4 were constructed. The cytotoxicity of liposomes with the oleoyl derivative in the human breast cancer cell culture turned out to be only three times lower than that of combretastatin A-4, thus indicating the probability of facile intracellular hydrolysis of the prodrug. To achieve selective drug delivery to the tumor tissue in vivo, the diglyceride conjugate of the tetrasaccharide ligand of selectins, viz., Sialyl-Lewis X (SiaLe^X, 2 mol.%) was incorporated into the liposomes. The SiaLe^X-equipped liposomes loaded with the lipophilic prodrug showed a reliable inhibition of tumor growth on the model of spontaneous breast cancer in mice.