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%.     

Electrochemical Reduction and Oxidation of 3,4-Disubstituted 1,2,5-Thiadiazoles

The electron-acceptor nitrogen and sulfur atoms in 3,4-disubstituted 1,2,5-thiadiazoles are responsible for much decreased reduction potentials and much increased oxidation potentials of these compounds compared with the corresponding carbocyclic derivatives. The thiadiazole ring is resistant to oxidation, and the reversible electron transfer gives rise to fairly stable radical cations. Reductive stability of the heterocycle depends on the nature of its substituents and on the medium: When nucleofuge substituents are present, two-electron transfer in aprotic media results in heteroring opening with iminonitrile formation, whereas in the presence of two readily leaving groups, the electron transfer induces cleavage of the complete heteroring into inorganic anions.     

Molecular and crystal structure of 1,3,10,12-tetraoxa-6,7,15,16-tetrathiacyclooctadecane recovered from a polysulfide oligomer

Conclusions The geometric parameters of the molecules of the main cyclic-fraction component contained in a polysulfide oligomer synthesized from 2,2-dichlorodiethylformal were determined. The cyclic structure assigned to this compound according to mass spectrometric data was confirmed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 338–340, February, 1988.The authors thank A. Kh. Plyamovatyi for-useful discussion of the present paper.     

Mass spectrometric investigation of the side-arm lariat effect of ortho- and para-methoxyphenoxymethyl-15-crown-5 in the gas phase

Mixtures of unsubstituted 15-crown-5 and its analogues containing ortho- and para-methoxyphenoxymethyl substituents with sodium salts were investigated by matrix assisted laser desorption/ionization (MALDI) mass spectrometry. Peaks of cationized molecules [M+Na]⁺ and cluster ions [2M+2Na+An]⁺, where M is the crown ether molecule and An is monobasic acid anion, were observed in the mass spectra. It was shown that an increase of the shielding degree of the sodium cation in complexes with crown ethers, i.e., the lariat effect, led to a significant decrease in the intensity of peaks of the cluster ions.     

α-Amino acetals containing a phosphonate or phosphine oxide group. Synthesis and reactions with resorcinols

New α-amino acetals containing a phosphonate or phosphine oxide group were synthesized by the Kabachnik-Fields reaction in the ternary system amino acetal-paraformaldehyde-dialkyl phosphonate (or dialkylphosphine oxide). Condensation of dialkyl (2,2-dimethoxyethylamino)methylphosphonates with resorcinol and its derivatives in ethanol in the presence of hydrochloric acid, apart from the corresponding 2,2-bis(polyhydroxyphenyl) ethylammonium salts, gave 2,5-bis(polyhydroxyphenyl)-1,4-bis[(dialkoxyphosphoryl)methyl]-piperazines. Dialkyl[(2,2-dimethoxyethylamino)methyl]phosphine oxides (Alk = C₈H₁₇, C₁₀H₂₁) did not react with resorcinol derivatives under similar conditions, and analogous ammonium salts were obtained by heating the reactants in boiling trifluoroacetic acid.     

Ring contraction of 1,3-bis(5-bromopentyl)alloxazine

The reaction of 1,3-bis(5-bromopentyl)alloxazine with ethylamine in propan-2-ol resulted in replacement of the terminal bromine atoms by ethylamino groups and was accompanied by contraction of the pyrimidine ring so that the products were 1,3-bis[5-(ethylamino)pentyl]alloxazine and 1,3-bis[5-(ethylamino)-pentyl]imidazo[4,5-b]quinoxalin-2-one.     

Structure of bucharaine

Conclusions From the plantHaplophyllum bucharicum Litv. have been isolated skimmianine, folifine, haplopine, and a new base, bucharaine.Bucharaine has the structure 4-(6-hydroxy-5-hydroxyisopropylhept-3-enloxy)quinol-2-one.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 394–397, 1969     

Synthesis and fluorescent properties of thiacalix[4]arenes containing terpyridyl fragments at the lower rim

New thiacalix[4]arenes tetrasubstituted by terpyridyl fragments at the lower rims in the 1,3-alternate stereoisomeric form were synthesized. The molecules interact with Eu^III and Tb^III in the DMF solution to form highly luminescent nanoscale (21–26 nm) metal-organic structures with the 2: 1 metal-to-ligand stoichiometry and a narrow particle size distribution.     

Phosphorylated Aminoacetal in the Synthesis of New Acyclic,Cyclic, and Heterocyclic Polyphenol Structures

New phosphorylated aminoacetal has been synthesized by the Kabachnik–Fields reaction; its reactivity has been studied in acid‐catalyzed condensation with linear polyphenols (2‐methylresorcinol, resorcinol, pyrogallol) and the Mannich reaction with macrocyclic polyphenol (calix[4]resorcinol). It has been determined for the first time that acid‐catalyzed reaction of phosphorus‐containing acetal with resorcinol and its derivatives in ethanol in the presence of hydrochloric acid gives new phosphorylated piperazines in addition to the compounds of diarylmethane series. Condensation of macrocyclic polyphenol (calix[4]resorcinol) with formaldehyde and N‐((dihexylphosphoryl)methyl)‐2, 2‐dimethoxyethylamine (the Mannich reaction) has resulted in novel tetrasubstituted calixarene containing aminophosphine oxide and acetal groups on the “upper rim” of molecule.