Conjugation effects and optical spectra of 1,2-diphosphole cycloadducts

Russian Chemical Bulletin - Quantum chemical calculations and a comparative analysis of Raman spectra of 3,4,5-triphenyl-1-propyl-1,2-diphosphole (1),...     

Diels-alder reaction of 1-methylcycloprop-2-ene-1-carbonitrile with methyl 2-oxo-2H-pyran-5-carboxylate

The Diels-Alder reaction of 1-methylcycloprop-2-ene-1-carbonitrile and coumalic acid methyl ester (methyl 2-oxo-2H-pyran-5-carboxylate) gave a 2:1 adduct with endo-syn configuration of both cyclopropane fragments, which was established by X-ray analysis. According to the ¹H NMR data, the reaction involves intermediate formation of decarboxylated 1:1 adduct having a cycloheptatriene structure; its isomerization into the corresponding caradiene, followed by addition of the second dienophile molecule, was confirmed by quantum-chemical calculations.     

Alkali metal polyphosphides as intermediates in the synthesis of organophosphorus compounds from elemental phosphorus

Russian Chemical Bulletin - Methods for the preparation of alkali metal polyphosphides, as well as their reactivity with respect to organic substrates, namely, electrophilic reagents and...     

Versatile Cycloaddition Reactions of 1-Alkyl-1,2-Diphospholes

Abstract

The reactivity of 1-alkyl-1,2-diphospholes in cycloaddition reactions with dienes, dienophiles or 1,3-dipoles was examined. 1-Alkyl-1,2-diphospholes (2 ) exhibit dual reactivity and act as diene toward maleic acid derivatives or as dienophiles with 2,3-dimethyl-1,3-butadiene. The 1-alkenyl-1,2-diphospholes (4 ) are readily involved in intramolecular [4 + 2] cycloaddition reactions leading to cage phosphines (5 ). Interaction of 1-alkyl-1,2-diphospholes (2) with 1,3-dipolar reagents (diphenyldiazomethane and nitrones) results in formation of the bicyclic phosphiranes (8) and dimers of 1-alkyl-1,2-diphosphole oxides (9) or bicyclic phosphine oxides (10) with a β-lactam moiety depending on temperature.     

Halogen Bonding Between Anions: Association of Anion Radicals of Tetraiodo-p-benzoquinone with Iodide Anions

Halogen bonding between two negatively charged species, tetraiodo-p-benzoquinone anion radicals (I₄Q^−.) and iodide anions, was observed and characterized for the first time. X-ray structural and EPR/UV–Vis spectral studies revealed that the anion–anion bonding led to the formation of crystals comprising 2D layers of I₄Q^−. anion radicals linked by iodides and separated by Et₄N⁺ counter-ions. Computational analysis suggested that the seemingly antielectrostatic halogen bonds in these systems were formed via a combination of several factors. First, an attenuation of the interionic repulsion by the solvent facilitated close approach of the anions leading to their mutual polarization. This resulted in the appearance of positively charged areas (σ-holes) on the surface of the iodine substituents in I₄Q^−. responsible for the attractive interaction. Finally, the solid-state associations were also stabilized by multicenter (4:4) halogen bonding between I₄Q^−. and iodide.     

Reactions of sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide with alkyl halides and silicon and tin chlorides

Reactions of sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide with primary alkyl bromides, secondary alkyl iodides, and silicon and tin chlorides gave stable 1-substituted 1,2-diphospholes. In a solution of 3,4,5-triphenyl-1-trimethylstannyl-1,2-diphosphacyclopenta-2,4-diene, the Me3Sn group migrates between two phosphorus atoms.     

Use of organosilicon compounds as modifiers of epoxy compositions

Organosilicon compounds used to improve the strength and adhesion properties, as well as the thermal stability, of epoxy compositions are reviewed. Properties of composition on the basis of bisphenol A-based ED-20 resin cured with a KrOOT-1 silicon-containing amine are described.     

Synthesis of alkali and heavy metal dithio- and thiocarbamates based on N-(Β-aminoethyl)piperazine

A series of alkali and heavy metal dithio- and thiocarbamates based on N-(-aminoethyl)piperazine and its derivatives N-(-piperazinoethyl)imides, N-[(-2,5-dimethyl-1-pyrrolyl)ethyl]piperazine, and N-(-salicylideneaminoethyl)-piperazine is prepared. Methods for preparation of dithio- and thiocarbamates based on piperazine are improved. Alkali metal dithio- and thiocarbamates based on piperazines form polymeric complexes with heavy metals.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1524–1528, November, 1989.     

Optically Active S‐Esters of Dithiophosphoric Acid on the Basis of (1S)‐endo‐(–)‐Borneol

The ammonium salt of optically active dithiophosphoric acid obtained by the reaction of tetraphosphorus decasulfide with (1S)‐endo‐(–)‐borneol reacts with benzoyl chloride, methyl chloroacetate and epichlorohydrin to form novel dithiophosphate S‐esters.