Cubane derivatives

New substituted cubane-1,4-dicarboxamides and 4-bromocubanecarboxamides containing the nitroxyl group and amino acid fragments along with the cubane skeleton were synthesized. The cardiac pharmacological activity (both the effect on aorta relaxation and the calcium channel blocking activity) of most of nitroxyalkyl derivatives is equal to or higher than that of N-(2-nitroxyethyl)nicotinamide (nicorandil).     

Perturbation calculation of oscillator strengths for the isoelectronic series of light atoms

Transition probabilities and oscillator strengths are calculated for the configurations 1s² 2sⁿ¹ and 1s² 2s^n1-1 2pⁿ²⁺¹, which are, respectively, of the form P=a/Z (1+/Z+) andf=/Z (1+/Z+). Numerical values are given fora, ,, and.     

O-acylated flavonoid glycoside of the needles ofPicea obovata

Summary From the needles of the Siberian spruce we have isolated a new diacylated flavonoid glycoside (I) for which we have established the structure of 3-(3-O-p-coumaroyl-6-O-feruloyl-glucopyranosyloxy)-4,5,7-trihydroxyflavone.The new acylated glucoside 6-O-feruloylastragalin (III) has been obtained and characterized for the first time.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. M. M. Sechenov First Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedirenii, No. 5, pp. 570–576, September–October, 1978.     

O-acylated flavonoid glycosides of the needles ofPinus sylvestris III. Di-p-coumaroyltrifolin

Summary A new diacylated flavonol glycoside has been isolated for the first time from Scotch pine needles, and for it the structure of 3,4,5,7-tetrahydroxyflavone 3-0-(3,6-di-O-p-coumaroyl--D-galactopyranoside) has been established.In the course of the chemical study of the compound isolated, the previously undescribed 6-O-p-coumaroyltrifolin was isolated and characterized.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. I. M. Sechenov First Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 332–336, May–June, 1978.     

Noncatalytic hydrophosphorylation and hydrothiophosphorylation of hydroxyaldehydes

Nucleophilic addition of secondary phosphone oxides and phosphine sulfides to 2-hydroxyacet-, 2-hydroxybenz-, and 3,4-dihydroxybenzaldehydes proceeds under mild conditions (48–50°C, THF) and allows tertiary phosphine oxides and phosphine sulfides with several hydroxyl groups to be prepared.     

N-Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis,Optical and Electronic Properties of D–π–A Compounds

N-heterocyclic olefins (NHOs), relatives of N-heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π-electron donating ability, NHOs were attached to triarylborane π-acceptors (A) giving donor (D)–π–A compounds 1 – 3 . In addition, an enamine π-donor analogue ( 4 ) was synthesized for comparison. UV–visible absorption studies show a larger red shift for the NHO-containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent-dependent emission studies indicate that 1 – 4 have moderate intramolecular charge-transfer (ICT) behavior. Electrochemical investigations reveal that the NHO-containing boranes have extremely low reversible oxidation potentials (e.g., for 3 , =−0.40 V vs. ferrocene/ferrocenium, Fc/Fc⁺, in THF). Time-dependent (TD) DFT calculations show that the HOMOs of 1 – 3 are much more destabilized than that of the enamine-containing 4 , which confirms the stronger donating ability of NHOs.     

Interactions between nonpolar surfaces in mixed solutions of cationic and nonionic surfactants

The interaction energy between hydrophobic SiO₂ particles in aqueous solutions of a cationic surfactant (dodecylpyridinium bromide, DDPB), a nonionic surfactant (Triton X-100, TX-100), and their mixed solutions was measured as a function of concentration. Synergism has been observed in mixed surfactant solutions: the surfactant concentration required for achieving the set interaction energy in the mixed solutions was lower than in the solutions of the individual surfactants. The molecular interaction parameters in surfactant mixtures were calculated using the Rosen model. Chain-chain interactions between nonionic and cationic surfactants were suggested as the main reason for the synergism.     

Semiempirical calculations of the electronically excited states of organometallic compounds: Selection of configuration interaction basis sets

Semiempirical INDO-E/S+RCIP calculations of the electronic structures of the ground and excited states of the pyrazine (pz) molecule and [Ru(NH₃)₅pz]^q (q=+1, +2, +3) complexes were performed to analyze the dependence of the calculation results on the active MO space and configuration basis set. Recommendations for the construction of the {Ф_k} basis sets and formation of the {ϕ_k} sets are given. St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 2, pp. 206–219, March–April, 1996. Translated by I. Izvekova     

Homolytic alkylation of quinaldine and quinoxaline with 18-crown-6

Homolytic alkylation of protonated quinoxaline with 18-crown-6, initiated by the system pivalic acid-iron(II) sulfate at 20–25C, gives (quinoxalin-2-yl)-18-crown-6 in 85% yield. Under analogous conditions, the reaction with quinoline affords two isomers: (quinolin-4-yl)-18-crown-6 and (quinolin-2-yl)-18-crown-6, in yields of 20 and 30% respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 75–76, January, 1988.     

Analysis of the effects of catalytic bleaching on cotton

Hydrogen peroxide can be catalyzed to bleach cotton fibers at temperatures as low as 30°C by incorporating dinuclear tri-μ-oxo bridged manganese(IV) complex of the ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (MnTACN) as the catalyst in the bleaching solution. The catalytic system was found to be more selective under the conditions applied than the non-catalytic H₂O₂ system, showing better bleaching performance while causing slightly lower decrease in degree of polymerization (DP) of cellulose. In order to gain fundamental knowledge of the bleach effect on cotton fibers and cellulose as its main component, especially after catalytic bleaching, X-ray Photoelectron Spectroscopy (XPS) was used to study surface chemical effects. The Washburn method was applied to investigate wetting properties, and liquid porosity was used to obtain pore volume distribution (PVD) plots. Parallel analyzes performed on model cotton fabric, i.e. “clean” cotton fabric stained with morin - a pigment regularly found in native cotton fiber, helped to differentiate between pigment oxidation and other bleaching effects produced on the (regular) industrially scoured cotton fabric. Bleaching was not limited to the chemical action but also affected cotton fiber capillary parameters most likely due to the removal of non-cellulosic materials as well as chain-shortened cellulose.