Yu. K. Voronina

An unusual conformation of 1,1′-dimethyl-isoindigo in crystals

The crystal and molecular structure of 1,1′-dimethyl-isoindigo is studied by single crystal X-ray diffraction analysis. It is shown that the molecules of 1,1′-dimethyl-isoindigo are nonplanar due to the rotation of two oxindole rings relative to the double bond.

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.

Synthesis of new α-aminophosphonates containing sterically hindered phenol fragments based on the reaction of 3,5-di(tert-butyl)-4-oxo-2,5-cyclohexadienylidenemethylphosphonates with aliphatic amines

A reaction of aliphatic amines (n-butylamine, sec-butylamine, tert-butylamine, dodecylamine, 1,12-diaminododecane) with α-phosphorylated methylenequinones (dimethyl {[3,5-di-(tert-butyl)-4-oxo-2,5-cyclohexadienylidene]methyl}phosphonate and diphenyl {[3,5-di(tertbutyl)-4-oxo-2,5-cyclohexadienylidene]methyl}phosphonate)) to form 1,6-nucleophilic addition products was studied. This approach was used to obtain a-aminophosphonates containing sterically hindered phenol fragments in high yields.

Molecular and crystal structure of 1-(2-hydroxyethyl)-1,2-dihydro-3,4,6-trimethyl-2-oxopyrimidinium iodide: the N-alkylation product of xymedone

The structure of xymedone iodo methylate is determined by X-ray crystallography. The molecular and crystal structure of the compound is analyzed in comparison with xymedone whose X-ray crystallographic data have been obtained previously. The molecular and electronic structures of both compounds and noncovalent interactions in the ionic pair of xymedone iodo methylate are analyzed using the data of the quantum topological calculations. It is shown that the presence of the iodine anion results in an increase in the delocalization of the π electron density inside the heterocyclic moiety, the charge redistribution inside the molecule, and consequently, in significant distinctions in crystal packings.

Crystallization of racemic 4-arylsulfonyl-2(5H)-furanones: Reproducibility of homochiral associates, conditions for the spontaneous resolution of enantiomers and the formation of racemic compounds, the role of intermolecular interactions

Crystallization of three 4-arylsulfonyl-2(5H)-furanones from chloroform leads to the formation of a conglomerate of sulfone with para-tolyl substituent and racemic crystals of chloro and bromo analogs. The high degree of similarity of the crystal packings of a homochiral crystal and racemic compounds, viz., the similar type of the homochiral hydrogen-bonded chains and analogous three-dimensional homochiral layers additionally stabilized by the interactions of the type C=O…C=O and C-H…O, allowed us to suggest the presence of the second, “missing” form for each sulfone. A directed search for the “missing” forms revealed the existence of the racemic modification of sulfone with the para-tolyl fragment formed during a very slow crystallization of the compound from benzene. No conglomerates of bromo and chloro analogs were found. Topological analysis of the electron density distribution performed by quantum chemical calculations using density functional theory (PBE1PBE, 6–31G(d,p)) showed the higher energy favorability of intermolecular interactions in the homochiral chains as compared to the hypothetical heterochiral associates.

Reactions of benzazole-2-thiones with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

The benzylation of benzothiazole(oxazole, imidazole)-2-thiones with 3,5-di-tert-butyl-4-hydroxybenzyl acetate involves either the sulfur or nitrogen atom depending on the reaction conditions. The S- and N-benzylation products of benzazole-2-thiones are kinetically and thermodynamically controlled products, respectively. The use of 3,5-di-tert-butyl-4-hydroxy-benzyl acetate allows sterically hindered hydroxybenzyl derivatives of benzаzole-2-thiones to be generally synthesized under milder conditions than in known methods of their synthesis.

Synthesis and structure of phosphorylated acetals

The Kabachnik-Fields reaction in a triple system (aminoacetal-paraform-diethyphosphite) resulted in the formation of the previously unknown aminophosphonates that contained the acetyl group and also their monoesters. Structures of the products were confirmed by 1H NMR, IR spectra and X-ray diffraction analysis. The MALDI mass spectra indicated that the presence of N-hydroxyethoxyphosphorylmethylaminomethyl groups underlies the ability of these compounds to self-assembly with the formation of n-dimensional H-bonded associations.

Cyclization of 1-(4,4-diethoxybutyl)-3-aryl(thio)ureas to 2-arylpyrrolidines and 2,3´-bipyrrole derivatives

A reaction of 1-(4,4-diethoxybutyl)-3-phenylthiourea with resorcinol, 2-methylresorcinol, pyrogallol, and hydroquinone in chloroform in the presence of trifluoroacetic acid leads to 2-aryl-1-(N-phenylcarbamothioyl)pyrrolidines. 1-(4,4-Diethoxybutyl)-3-arylureas and 1-(4,4diethoxybutyl)-3-arylthioureas in the presence of an acid catalyst undergo intramolecular cyclization and dimerization with the formation of 1,1´-bis(N-arylcarbamo(thio)yl)-2,3´-bipyrrole derivatives.

The lp(O)...π-interactions in 1-[1-(methoxycarbonylmethylthio)methyl]-3,5-dimethylisocyanurate: topological analysis of the electron density distribution from X-ray diffraction data and quantum chemical calculations

The intra- and intermolecular interactions that make a major contribution to the formation of the crystal structure were detected and characterized in the crystal of 1-[1-(methoxycarbonylmethylthio)methyl]-3,5-dimethylisocyanurate. Topological analysis of the experimental and theoretical electron density distribution was used to reveal for the first time the role of the lp(O)...π interaction in the formation of a crystal of an isocyanurate derivative and to estimate its energy. Interactions of this type were found to occur in 74% of the fully N-substituted isocyanurate structures.

Synthesis and dimerization of dibutyl (3,5-di -tert -butyl-4-oxo-2,5-cyclohexadienylidenemethyl)phosphonate

While studing the synthesis and properties of phospho rylated methylenequinones,1—5 we have accessed dibutyl (3,5 di tert butyl 4 oxo 2,5 cyclohexadienylidenemeth yl)phosphonate (1) by oxidation of dibutyl (3,5 di tert butyl 4 hydroxybenzyl)phosphonate (2) with alkaline po tassium ferrihexacyanide (Scheme 1). The structure and composition of compound 1 were established based on the 1H, 31P NMR and IR spectro scopic data, mass spectrometric (MALDI) data, and ele mental analysis. We found that with time compound 1 undergoes dimerization leading to 1,2 bis(dibutoxyphos phoryl) 1,2 bis(3,5 di tert butyl 4 hydroxyphenyl)ethane (3). The process reached completion within 10 days, which was indicated by the disappearance in the 31P NMR spec trum of the signal for the starting compound 1 (P 15.0) and the presence of the only singlet for the dimerization product 3 (P 27.5). The structure and composition of compound 3 were confirmed by the 1H, 31P NMR and IR spectroscopic data, mass spectrometric (MALDI) data, elemental analysis, and X ray diffraction studies (Fig. 1). It should be noted that in the solution in benzene, methylenequinone 1 did not undergo visible changes over prolonged period of time.