Yu. Ya. Efremov

Oxidation of prochiral sulfides with chiral dioxirane

Dioxirane generated in situ by reaction of chiral 1,2:4,5-di-O-isopropylidene-D-erythro-hexo-2,4-diulo-2,6-pyranose with Oxone oxidizes prochiral sulfides to the corresponding sulfoxides with an enantiomeric excess of 2 to 25%.

Synthesis of pyrimidinocyclophanes having a bridging nitrogen atom

Reactions of 1,3-bis(ω-bromoalkyl)-substituted uracils, quinazoline-2,4-dione, and 5-methyl-1,3,5-triazine-2,4,6-trione and 1,3-bis(m-bromomethylbenzyl)-5-bromouracil with amines (aliphatic amines, benzylamines, naphthylmethanamine, and anisidine) gave a series of macrocyclic compounds having one pyrimidine or triazine fragment and an azapolymethylene bridge connecting the N1 and N3 atoms of the heteroring. The bridging nitrogen atom in some macrocyclic compounds was subjected to quaternization with methyl p-toluenesulfonate.

Reactions of phenylenedioxytrihalophosphoranes with arylacetylenes: VII. Reaction of 2,2,2-trichloro-4-fluoro-1,3,2λ5-benzodioxaphosphole with phenylacetylene

Abstract2,2,2-Trichloro-4-fluoro-1,3,2λ5-benzodioxaphosphole reacts with phenylacetylene to give 2,7-dichloro-5-fluoro-4-phenyl-2H-1,2λ5-benzoxaphosphinine 2-oxide. Hydrolysis of the latter leads to opening of the oxaphosphinine ring with formation of (E)-2-(4-chloro-2-fluoro-6-hydroxyphenyl)-2-phenylethenylphosphonic acid.

Synthesis and antimicrobial activity of pyrimidinophanes with two uracil units and bridging nitrogen atoms

A series of pyrimidinophanes containing two uracil units and nitrogen atoms in bridging polymethylene chains –(CH2)nN(Et)(CH2)m– (n, m = 5, 6) have been synthesized. The uracil moieties are represented by 6-methyl-, 5-decyl-6-methyl-, and 5-fluorouracils. Quaternization of the bridging N atom with ethylbromide or n-decylbromide yielded amphiphilic pyrimidinophanes, which were evaluated for their antibacterial and antifungal activity in terms of minimal inhibiting concentration (MIC) against Gram-positive and Gram-negative bacteria and fungi. It has been found that MICs of the amphiphilic pyrimidinophanes decrease with increasing lipophilicity of the alkyl substituents at the bridging N atoms and with increasing polymethylene N(pyr)–N chain length (in some cases MIC against Staphylococcus aureus is below 1 ìg/mL). The MICs increase dramatically upon introduction of lipophilic n-decyl substituents at C(5) atoms of the uracil moiety. The results can be used in the search for new highly effective antimicrobial agents.

Synthesis of pyrimidinophanes containing nitrogen atoms in polymethylene bridges

The reactions of 1,3-bis(ω-bromobutyl- or -pentyl)-6-methyluracil with 1,3-bis(ω-ethylaminobutyl- or -pentyl)-6-methyluracil afforded pyrimidinophanes containing N atoms in bridging polymethylene chains. Individual geometric isomers of pyrimidinophanes were isolated. The structure of one of these isomers was established by X-ray diffraction analysis. Quaternization of the bridging N atoms with o-nitrobenzyl bromide gave rise to water-soluble pyrimidinophanes.

Synthesis, IR Spectra, and Steric Structure of Macrocycles Derived from Pyrimidine Compounds

A new macrocycle including pyrimidine fragments, 12,23,36-trimethyl-24,40-dioxo-15,33-dithia-2,9,13,22,26,35,38,39-octaazatetracyclo[32.3.1.110,14.122,26]tetraconta-1(38),10(39),11,13,23,34,36-heptaene, was synthesized. According to the data of IR and UV spectroscopy and HF/6-31G** quantum-chemical calculations, macrocyclic compounds of this series in crystal exist in the amino form, one NH group of which is likely to be involved in intramolecular hydrogen bond, and the other, in intermolacular hydrogen bond. The strength of the latter depends on the macroring size. In solution, the above structures are supplemented by conformers containing both intramolecularly H-bonded and free amino groups, predominantly with trans structure of the HÄNÄCÍN fragment. The imino form of the aminopyrimidine moieties is hardly probable.

Synthesis and some properties of o-borylphenylphosphine

Abstract(o-Dibutylboryl)diphenylphosphine, containing tricoordinated phosphorus and boron atoms, was obtained for the first time in the reaction of (o-bromo-phenyl)diphenylphosphine, butyllithium, and butylchloroborane. Analysis of the spectral indices and their comparison with reported data showed the lack of stabilizing donor-acceptor interactions between phosphorus and boron atoms.

1-Dibutylboryl-2-diphenylphosphinoethene and its derivatives

Abstract1-Butyl-1-dibutylboryl-2-diphenylphosphino-2-phenylethene, which exists in the form 1,1,2-tributyl-3,4,4-triphenyT-1-borata-4-phosphoniacyclobut-2-ene, reacts with sulfur, selenium, methyl iodide, and pyridine under mild conditions with ring cleavage. In (2-butyl-2-dibutylboryl-1-phenylethenyl) diphenylphosphine sulfide and selenide, there is a coordinate bond between the thio-or selenophosphoryl group and the boron atom.

Reactions of Pyrimidinophanes and Their Acyclic Analogs with Electron-Deficient Substrates

Acyclic and macrocyclic compounds having different numbers of pyrimidine fragments and nitrogen atoms in the polymethylene bridges or in substituents at the pyrimidine rings reacted with 2,3,5,6-tetrachloro-1,4-benzoquinone and 1,4-benzoquinone according to the charge transfer scheme to give products with an ionic structure. The reaction was accompanied by protonation of nitrogen atoms in the polymethylene bridges or in substiuents at the pyrimidine rings and reduction of 2,3,5,6-tetrachloro-1,4-benzoquinone or 1,4-benzoquinone to 2,3,5,6-tetrachlorobenzene-1,4-diol or benzene-1,4-diol, respectively. The isolated products are dielectrics.

Imidazo[1,5-a]- and Thiazolo[3,4-a]quinoxalines Based on 3-(a-Thiocyanobenzyl)quinoxalin-2(1H)-one

When 3-(a-thiocyanobenzyl-2(1H)-one is heated, competing processes of [a]-annelation of the imidazole or thiazole rings occurs with formation of imidazo[1,5-a]- and thiazolo[3,4-a]quinoxalin-4(5H)-ones.