127I NQR spectra of carborane-containing compounds of polycoordinated iodine

Conclusions A considerable increase in the quadrupole coupling constants (e²Qq_zz) and significant decrease in the asymmetry parameter is found in carborane-containing CBICl₂ and PhCBIX compounds in comparison with the corresponding phenyl and diphenyl derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2622–2623, November, 1984.     

Interactions of carborane-containing electrophiles with triethyl phosphite. Synthesis of new carborane-containing phosphonates

The reactions ofo-carboran-l-ylethyl mesylates with triethyl phosphite and sodium diethyl phosphite were studied. Carborane-containing phosphonates were synthesized. The reaction ofo-carboranylacetyl chloride with triethyl phosphite affordedO,O-diethyl (E)-2-(o-carboran-l-yl)-1-(o-carboran-1-ylacetoxy) vinylphosphonate rather than oxo phosphonate. Dedicated to the memory of Academician M. I. Kabachnik on his 90th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2041–2044, October, 1998.     

Approaches to the preparation of (Z)-1,2-difluorostilbenes

Methodology directed at the preparation of (Z)-1,2-difluorostilbenes has been evaluated. For symmetrical (Z)-1,2-difluorostilbenes, photochemical isomerization of the isomeric (E)-1,2-difluorostilbenes, and HPLC separation of the mixture of stilbene isomers is a reasonable route to a particular (Z)-stilbene. An alternative approach to both symmetrical and/or unsymmetrical (Z)-1,2-difluorostilbenes has been developed via stereospecific Pd(0) coupling of (E)-1,2-difluoro-aryl-ethenyltributylstannanes under Stille-Liebiskind conditions with aryl idodies. The requisite arylstannanes can be obtained via the reported route developed by Davis or via (E)-1,2-difluorovinyltributylstannane - a new route described in this work. The methodology tolerates almost any functionality in the aryl ring, is easily carried out, is stereospecific and provides the first general route to (Z)-1,2-difluorostilbenes.     

Synthesis of novel carborane-containing terminal alkynes

Lithiation of 1-bromomethyl-o-carborane with lithium diisopropylamide (LDA) in THF results in the in situ formation of 1-lithio-2-bromomethyl-o-carborane, the reaction of which with 3-trimethylsilylprop-2-ynal gives 2-(2-trimethylsilylethynyl)-3,4-(о-carborano)-2,5-dihydrofuran. Subsequent base-catalyzed desilylation furnishes new terminal alkynes of closoand nido-carborane series.     

Alkylation of aromatic compounds with pummerer rearrangement intermediates. Application to the preparation of methyl-aryl compounds

Pummerer intermediates generated from dimethylsulfoxide reacted with aromatic compounds in the presence of tin (IV) chloride to give methyl-thiomethylaryl products which were in turn desulfurized to methylaryl compounds with Raney-Ni.     

The preparation of radiobromine-labelled compounds

A rapid and direct method for the production of a number of carrier-free radiobrominated compounds is described, [⁷⁷Br]-5-Bromo-2’-deoxyuridine is shown to be taken up by actively growing E. Coli cultures and incorporated into cellular nucleic acids.     

手性联苯类化合物的制备

手性联苯化合物在有机合成和天然产物化学中都有相当重要的地位,本文论述了近年来得到手性联苯类化合物的一些方法。     

Investigation of anaerobic compositions based on carborane-containing oligoester acrylates

The possibility of considerably improving the thermal stability of anaerobic glue compositions at the expense of introducing carborane groups in the oligomer structure was shown. The influence of initiating and inhibiting components based on the properties of anaerobic compositions was investigated.     

Synthesis of carborane-containing phosphates by catalytic phosphorylation

The catalytic phosphorylation ofo-carboranylmethanol with different phosphorus acid chlorides has been studied. This method makes it possible to obtain esters of phosphorus acids and esters of the corresponding phosphorus acid chlorides containing carboranylmethyl groups. The catalytic phosphorylation of 1,2-bis(hydroxymethyl)-o-carborane affords both acyclic and cyclic phosphate esters. The structure of the synthesizedo-carborano[1,2-e]-1,3,2-dioxaphosphepane was confirmed by X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 145–149, January, 1995.     

The preparation of macrocyclic polyether-diester compounds by transesterification including the preparation of two new nitrogen containing diester-crown compounds

Macrocyclic polyether-diester compounds have been prepared by reacting oligoethylene glycols with the appropriate dimethyl esters in the presence of catalytic amounts of alkali metal methoxides. The methanol by-product was removed by molecular sieves. Product yields were improved for the preparation of all macrocyclic compounds except a compound containing a furan subcyclic group ( 4 ). Six new macrocyclic diester compounds ( 7-12 ) could only be prepared using the base catalyzed transesterification process since the acid chloride synthetic method failed or the acid chloride could not be made. The formation of compounds 5 and 6 from dimethyl 2, 6-pyridine dicarboxylate ( 17 ) and the triethylene and tetraethylene glycols proceded by way of half-transesterified intermediates. These intermediates were also observed for the base catalyzed decomposition of 5 and 6 in methanol to form the glycol and the diester 17 .     

Approaches to increasing the sensitivity of the determination of phenolic compounds using chitosan-based solid-phase optical biosensors

It was shown that the sensitivity of the determination of phenolic compounds using chitosan-based optical biosensors could be increased by varying the sorption conditions of products of enzymatic oxidation of phenolic compounds. Sorption isotherms of oxidation products of phenolic compounds by a chitosan film were studied according to Langmuir and Freundlich models. Quantitative characteristics of the sortpion process, such as maximum sorption capacity, the Langmuir isotherm constants, and the Gibbs free energy were determined.     

Electrochemical preparation of some organotin compounds

Organotin dihalides R₂SnX₂ (X  Cl, Br, I) and their adducts with bidentate donor ligands have been prepared in high yield by the direct electrochemical reaction of metallic tin with alkyl or aryl halides in organic media at room temperature. Dimethyltin diiodide can be converted to tetramethyltin by reaction with methyl iodide at a cadmium anode. Electrochemical halide abstraction has been used to prepare R₆Sn₂ (R  Me, Ph) from the corresponding R₃Sn halide. The mechanism of these reactions is discussed.     

An expedient enantioselective route to diaminotetralins: application in the preparation of analgesic compounds

Advances to the rhodium-catalyzed asymmetric ring-opening protocol have allowed this methodology to be extended to azabicyclic alkenes, the first time that rhodium has been used in allylic functionalizations with nitrogen leaving groups. The product diaminotetralins are important medicinal compounds. The synthetic utility of this methodology has been demonstrated in the total synthesis of an analgesic compound where the tetralin core, the regiochemistry, and the relative and absolute stereochemistry are all established in the ring-opening step. [reaction: see text]     

Water-soluble carbosilane dendrimers protect phosphorothioate oligonucleotides from binding to serum proteins

Treatment of dendriplexes formed between water-soluble carbosilane dendrimers and phosphorothioate oligodeoxynucleotides (ODN) with the anionic detergent sodium dodecyl sulfate disrupted the complexes indicating that the nature of the union in such dendriplexes is merely electrostatic. However, dendriplexes were not dissociated by serum proteins like bovine or human serum albumins, as assessed by gel electrophoresis and fluorescence experiments. This would imply a dendrimer-mediated protective effect able to prevent ODN interactions with serum proteins and additionally could translate into a reduction of the ODN doses needed to achieve the biological effects. The employment of carbosilane dendrimers as carriers may solve the problem of ODN kidnapping by plasmatic proteins as a key drawback for therapeutics involving ODNs. As examples, transfection processes on normal primary peripheral blood cells and diagnosis of HIV infection in the presence of serum have been assayed.     

A preparation of bromoolefins from carbonyl compounds

A variety of 1-bromoalkenes are prepared by addition of dibromomethyllithium to ketones and aldehydes followed by reductive elimination with zinc-acetic acid. The product E/Z ratios were determined, and halogen-lithium exchange with t-butyllithium was examined.     

Effective preparation of cycloheptimidazol-4-one compounds

Effective preparation of cycloheptimidazol-4-ones was developed. The reactions of 2-tosyloxytropone (5) with amidines (6) carried out under simple conditions such as aq. NaOH in toluene at 35 degrees C afforded the corresponding cycloheptimidazol-4-ones (3) in low yield. However, by adding tetra-n-butylammonium bromide (n-Bu(4)NBr) to this reaction system, the yield was improved dramatically. The reaction conditions were screened in detail.