Synthesis of Aryloxy-Substituted 1,2,5-Thiadiazoles by the Ullmann Reaction

3-Aryloxy-1,2,5-thiadiazoles were synthesized by the Ullmann reaction either from 3-chloro-1,2,5- thiadiazoles and phenols having donor substituents or from 3-hydroxy-1,2,5-thiadiazoles and chlorobenzenes containing acceptor substituents.     

Comparative analysis of the binding of thiacalix[4]arene-monocrown-ethers with monovalent metal salts using MALDI mass spectrometry

MALDI mass spectrometry is used for the first time for the rapid assessment of the binding of thiacalix[4]arene-monocrown-ethers with metal cations (Li, Na, K, Cs, Cu, Ag). The work is performed on examples of thiacalix[4]arene-monocrown-ethers in 1,3-alternate conformation with various numbers (m) of ethylene oxide units and various substituents in phenol groups. It is shown that thiacalix[4]arene-monocrown- ethers with m = 3, 4, 5, and 6 bind lithium, sodium, potassium, and cesium cations, respectively; in addition, the binding of cesium cations is stronger in the presence of aromatic substituents in the lower rim of thiacalix[4]arene-monocrown-ethers. Silver cations bind with calixarenes under study more intensely than copper ions. When aromatic substituents are present, the binding of silver cations is stronger than that of alkali metal ions with the studied thiacalix[4]arene-monocrown-ethers.     

A Comparative Study of the Cyclic Chlorophosphites with C2-Symmetrical Organic Fragments as the Reagents for Enantiomeric Composition Control of the Chiral Alcholos

Abstract

The ³¹P NMR method is intensively used for enantiomeric composition control during the last years [1]. Among all other derivatizing agents the C₂-symmetrical ones have some advantages.     

On the use of seven-membered phosphorous heterocycles based on 2,2′-dihydroxy-1,1′-binaphthalene and 1,4∶3,6-dianhydro-d-mannitol in the31P NMR analysis of the enantiomeric composition of chiral alcohols

Some aspects of phosphorylation of 2,2′-dihydroxy-1,1′-binaphthalene (BINOL) and 1,4∶3,6-dianhydro-d-mannitol (isomannide) were investigated. The possibility of using the corresponding cyclic chloro- and amidophosphites for the analysis of enantiomeric compositions of chiral primary and secondary alcohols by³¹P NMR was examined. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 426–431, March, 1998.     

Conversions of 2-Phenyl-1,3,2-dioxaphospholane Under the Action of Hydrogen Chloride

The reaction of 2-phenyl-1,3,2-dioxaphospholane with HCl gives a mixture of phenylphosphinic acid, bis(2-chloroethyl) phenylphosphonate, and phenylphosphine; therewith, intermediate oligomeric phosphonites, hydrophosphoryl compounds, and phosphoranes were detected. Thermal treatment of the reaction mixture results in formation of ethylene phenylphosphonate and (2-chloroethyl)phenylphosphinate.     

Stereochemistry of 1,3-diheterocyclanes 4. Molecular and crystal structures of monosubstituted five-membered cyclic sulfites

Racemic and enantiopure cis-and trans-4-(1-naphthyloxy)methyl-2-oxo-1,3,2-dioxathiolanes were studied by X-ray diffraction. The factors responsible for their crystal packings were revealed. The conformation of the exocyclic fragment varies from synclinal to antiperiplanar depending on both the local (cis-trans isomerism of the molecule) and external (homochiral/heterochiral environment) stereochemical factors. Data on the structures of five-membered sulfites in crystals were generalized. It was concluded that the heterocycle has considerable conformational flexibility. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1095–1102, July, 2006.