Crystal and Molecular Structure of Ph3P+-CH = CH-NHC6H3(2-O-)(4-NO2)

Treatment of [Ph₃P⁺-CH = CH-NHC₆H₃(2-OH)(4-NO₂)]Cl^- with ethanolic KOH leads to proton abstraction not from nitrogen, but from oxygen to give a betaine-type compound Ph₃P⁺-CH = CHNHC₆H₃ · (2-O^-)(4-NO₂). Its structure was proved by means of X-ray diffraction. The C = C distance [1.341(3) Å] unambiguously points to a double bond. Single crystals of the betaine are monoclinic, space group P2(1)/c; unit cell parameters: a 9.028(4), b 14.066(6), and c 18.799(10) Å; 90, 76.23(4), and 90°. The unit cell contains two dimers bound by strong inter- and intermolecular hydrogen bonds. Previously published IR and ¹H NMR data do not contradict the betaine structure of the compound obtained.     

Chemical communication between solids placed at distance: Sol-gel entrapped acids and bases

Chemical reactions between “far-away” components are quite common in the living world and in geological processes, and are affected by communicating shuttling molecules and ions. Surprisingly, there has been little attention in the chemical literature to model these natural processes by bench-laboratory heterogeneous reactions. Towards that goal we report the study of chemical communication between solid acids and bases placed at distance. The porous solids were prepared by entrapping various acids and bases in silica sol-gel matrices. We recall that while, of course, dissolved acids and bases titrate each other, when solid acids and bases are placed in the same pot, titration can be affected only through an ion-exchange process. This property is used here to cause the two distantly placed solids to communicate with each other. In particular, we use here the entrapped acids as senders of messenger-hydronium ions and as receivers of hydroxyl ions, and entrapped bases as senders of messenger-hydroxyls. We demonstrate the possibility to control the parameters of the communication between these solids.     

Spirolactams as conformationally restricted pseudopeptides: synthesis and conformational analysis

The synthesis of 1-(tert-butoxycarbonyl)-7-[1-(tert-butoxycarbonyl)-3-methylbutyl]-6-oxo-1,7-diazaspiro[4.5]decanes (S,S)-1a and (S,R)-1b is described. Derivatives 17a,b and 19a are prepared for use in peptide synthesis as constrained surrogates of the Pro-Leu and Gly-Leu dipeptides. The Ac-[Gly-Leu]-Met-NH(2) derivatives (S,S,S)-2a and (S,R,S)-2b, with the tripeptidic C-terminal region present in tachykinins, are also synthesized. Conformational analyses of these tripetide analogues by NMR experiments and molecular modeling calculations show that both (S,S,S)-2a and (S,R,S)-2b epimers are gamma-turn/distorted type II beta-turn mimetics.     

Mild Pfitzner—Moffat oxidation of the (1→3)-β-D-glucan from Saccharomyces cerevisiae

The structure of the cell wall glucan isolated from the industrial strain of Saccharomyces cerevisiae was characterized as to be composed of a linear (1→3)-β-D-glucan chain with single β-D-glucopyranosyl residues attached to every ninth backbone unit by (1→6)-glycosidic linkages. Mild oxidation of this β-D-glucan with a dimethyl sulfoxide—acetic anhydride reagent yielded an “oxidized” glucan with aldehyde groups introduced at C-6 and carbonyl oxygens located at C-2 and C-4 of the glucopyranosyl rings. The conversion of the oxidized glucan into the polyoxime was used to study the progress of oxidation and to establish the carbonyl groups distribution in this new reactive polysaccharide derived from baker’s yeast cell wall.     

Substrate specificity of microbiological conversions of steroids by means ofActinomyces albus ATCC 3006

Summary In a comparison of the substrate specificity of the action of a culture ofActinomyces albus 3006 and a cell-free preparation obtained from the mycelium ofA. albus 3006, it was found that the spectrum of the action of the steroid oxidoreductase ofA. albus is broader than the spectrum of the action of the culture. Some of the factors responsible for the difference in the specificity of the action of the culture of the microorganism and the enzyme preparation are examined.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 2, pp. 100–107, 1965     

Crystal structure of bis-Isonicotinoyl hydrazone of 2,5-diformylpyrrole

bis-Isonicotinoyl hydrazone of 2,5-diformylpyrrole existing in the crystal in the form of a tetrahydrate of the hydrazone tautomeric form is synthesized and its structure is described. In the crystal, an infinite three-dimensional network of hydrogen bonds is formed by hydrazone molecules. The neighboring hydrazone molecules are bonded by intermolecular π stacking interactions. A quantum chemical calculation of the geometry and total energy of possible tautomers in vacuum and an aqueous solution is performed.     

Double-Membrane Sampling System in a Mass Spectrometer for the Study of Exhaled Air

Technical Physics - A double-membrane sample-introduction system is described that enables mass spectrometric determination of volatile organic compounds in air, while ensuring their detection...     

Cannabinoid Quinones—A Review and Novel Observations

A cannabinoid anticancer para-quinone, HU-331, which was synthesized by our group five decades ago, was shown to have very high efficacy against human cancer cell lines in-vitro and against in-vivo grafts of human tumors in nude mice. The main mechanism was topoisomerase IIα catalytic inhibition. Later, several groups synthesized related compounds. In the present presentation, we review the publications on compounds synthesized on the basis of HU-331, summarize their published activities and mechanisms of action and report the synthesis and action of novel quinones, thus expanding the structure-activity relationship in these series.     

Electronic structure of chelate compounds of nickel(II) with azo compounds (coordination sites [2N, 2N], [2O, 2N], and [2S, 2N])

Journal of Structural Chemistry -