Reactions of trimethinecyanines of the 1,3-dioxenium series with nucleophiles. The structures of the parent carbocation and of a product of its reaction with methanol

The chemistry and the regioselectivity of alcoholysis, aminolysis, and hydrolysis of symmetrical trimethinecyanine carbenium ions in 4-[3-(2,2-diorganyl-6-phenyl-4H-1,3-dioxen-4-ylidene) prop-1-enyl]-2,2-diorganyl-6-phenyl-1,3-dioxenium perchlorates (4a,b) were investigated. The structures of trimethinecyanine 4,5:4′,5′-bisannelated at the methine chain (3) and of a product of the reaction of nonannelated trimethinecyanine with the methoxide anion were established by X-ray diffraction analysis,¹H NMR spectroscopy, and quantum-chemical calculations (PM3). The nucleophile attacks the mesomeric π-conjugated system of the trimethinecyanine cation selectivily at the C(6) atom of one of the dioxenium fragrments, the second dioxenium ring being deactivated. Alcoholysis affords products of addition of the methoxy group to trimethinecyamines. In the course of aminolysis and hydrolysis, the dioxenium ring that is subjected to the attack eliminates acetone to form 1,3-dioxenylidenepropenylic derivatives of 1,3-enaminoketones and 1,3-ketoenols, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 521–529, March. 1999.     

Quaternary ammonium salts as alkylating agents in the synthesis of tertiary phosphine oxides

A procedure was developed for the synthesis of tertiary phosphine oxides by alkylation of secondary phosphine oxides with quaternary ammonium salts. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 390–392, February, 1999     

Efficient synthesis of [1,2,3]triazolo[5,1-c][1,4]benzoxazines through palladium-copper catalysis

A wide variety of [1,2,3]triazolo[5,1-c][1,4]benzoxazines were synthesized through palladium-copper catalyzed reactions of 1-azido-2-(prop-2-ynyloxy)benzene with aryl/vinyl iodides. A plausible reaction mechanism has also been proposed.     

The production of prop-2-ynylideneamine by thermolysis of N-chloropropargylamine,N-fluoropropargylamine and N-hydroxypropargylamine: a computational study

Ab initio molecular orbital calculations using MP2 and DFT/B3LYP methods at the 6-311++G(d,p) and aug-cc-pvdz basis sets were applied to characterise the kinetics of the thermal dissociation of HC≡CCH₂NHX [where X = OH(I), F(II) and Cl(III)] to produce Z- and E-prop-2-ynylideneamines (HC≡CCH=NH) (IV and V, respectively), which tautomerise to vinyl cyanide (CH₂=CHC≡N) (VI). The optimised geometries and electronic energies of reactants, transition states and products were estimated and discussed. A concerted proton migration and HX abstraction mechanism was proposed for the imine formation. The reliance of these properties on the elected levels of theory was discussed. The activation energies and barrier heights for the Z- and E-forms and their vinyl cyanide tautomers were estimated and analysed. The Z-form was computed to be more stable than the E-form. Using natural bond orbital calculations, the origin of the preference of the Z-form was attributed mainly to the N lone pair delocalisations. Vinyl cyanide was located to have a lower energy (33–35 kcal/mol) than prop-2-ynylideneamine. The provenance of the preference of the former and its tautomerisation mechanism will be addressed in a separate publication.     

Synthesis of 3-hydroxy-1-methyl-2-(methylthio) pyrrole from methyl isothiocyanate and prop-2-yn-1-ol

A methylated adduct of lithiated 1-(1-ethoxyethoxy)allene and methyl isothiocyanate undergoes intramolecular cyclization in the presence of CuBr to give 3-(1-ethoxyethoxy)-1-methyl-2-(methylthio)pyrrole. The methanolysis of the latter affords 3-hydroxy-1-methyl-2-(methylthio)pyrrole. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1645–1647, September, 2000.     

Study of the behavior of p-bis{3-[N,N-dialkyl-N-(4-hydroxybut-2-ynyl)ammonio]prop-2-ynyl}-benzene dichlorides in relation to aqueous alkali. Double intramolecular recyclization of benzo[5,6;5′,6′-a,c]di(2,2-dialkyl-4-hydroxymethyl)isoindolinium dichlorides

p-Bis{3-[N,N-dialkyl-N-(4-hydroxybut-2-ynyl)ammonio]prop-2-ynyl}benzene dichloride in the presence of catalytic amounts of aqueous alkali is subject to a double intramolecular cyclization forming benzo[5,6;5′,6′-a,c]di(2,2-dialkyl-4-hydroxymethyl)isoindolinium dichloride in 40–42% yield. Simultaneously an intramolecular recyclization takes place with the formation of dialkyl(6-dialkylaminomethyl-7,9,10,12-tetrahydro-8,11-dioxadicyclopenta[c,g]phenanthren-1-ylmethyl)amines in 7–9% yield. The same compounds are obtained in 70–72% yield by the recyclization of benzo[5,6;5′,6′-a,c]di(2,2-dialkyl-4-hydroxymethyl)isoindolinium dichlorides under conditions of aqueous alkaline degradation. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1329–1335, September, 2006.     

Rearrangements of diferrocenylcyclopropenium ions in the reactions with bis-1,4-O,S-nucleophiles

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Synthesis and properties ofN-[1-hydroxyimino-2-methyl-1-(2-pyridyl)prop-2-yl]hydroxylamine and heterocyclic derivatives based on it

N-[1-Hydroxyimino-2-methyl-1-(2-pyridyl)prop-2-yl]hydroxylamine, a new representative of the series of α-hydroxylamino oximes, was synthesized. Based on this compounds, 3-imidazoline 3-oxide and 2-imidazoline 3-oxide derivatives, were obtained, and some of their chemical properties were investigated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 131–136, January, 1997.     

Regioselective synthesis of polysubstituted 4H-thiopyrans from β-oxodithioesters

A simple and efficient method for the synthesis of polyfunctionalized 4H-thiopyrans by highly regioselective cyclocondensation of β-oxodithioesters with 1,1,3-trialkyl or aryl substituted prop-2-yn-1-ols using BF₃·Et₂O as the catalyst is described.