New indoline spiropyrans with π-acceptor substituents in the 8′ position

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1700–1701, December, 1990.     

Reactions of 10-telluroniaanthracene perchlorates with nucleophiles

10-Telluroniaanthracene perchlorates react with nucleophiles (X^–=halide, hydroxide, methoxide) via intermediate free telluroxanthyl radicals. With 9-aryl-10-telluroniaanthracene perchlorates, high yields of 9-aryl-9-X-telluroxanthenes are obtained, but with 10-telluroniaanthracene the principal product is 9,9-bis(telluroxathenyl) as a result of rapid competitive dimerization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 691–695, May, 1989.     

Synthesis and reactivity of ethoxyvinyl derivatives of 1,3-dioxolanium salts

2-(-Ethoxyvinyl)dioxolanium salts were obtained by reaction of ortho esters with 2,4,4,5,5-pentamethyl-1,3-dioxolanium perchlorate in acetic anhydride. Alkaline hydrolysis of 2-(-ethoxyvinyl)-4,4,5,5-tetramethyl-1,3-dioxolanium perchlorate leads to the corresponding ,-unsaturated aldehyde. Substituted 2-(-aminovinyl)-1,3-dioxolanium perchlorates are formed by reaction of this salt with aromatic amines, amino acids, and urea. These perchlorates readily split out perchloric acid in alkaline media to give Schiff bases. The charges and electron densities were calculated for the 2-(-methoxyvinyl)-1,3-dioxolanium cation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1614–1617, December, 1973.     

Electronic structure of perimidine

The electronic configurations and dipole moments of the ground and excited states of perimidine, imidazole, and benzimidazole were calculated by means of the self-consistent-field molecular orbital (SC F MO) method using the Pariser-Parr-Pople (PPP) approximation. The reactivity of perimidine is discussed. The results of the calculations by the PPP method are compared with earlier calculations based on the simple MO method. An interpretation of the electronic spectrum of perimidine is given.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 678–681, May, 1971.     

Theoretical Modeling of the Stereoisomerization of Tetracoordinated Be(II) Bis(chelate) Complexes

Quantum-chemical (semiempirical MNDO and ab initio RHF SCF with an STO-3G basis set) calculations were performed for stereoisomerization of tetracoordinated Be(II) bis(chelate) complexes with BeN₂O₂ coordination unit. The most probable pathway for their monomolecular isomerization was found to involve, in agreement with experimental data, cleavage of a Be–N coordination bond to form a tricoordinated Be intermediate (dissociation–recombination mechanism) rather than a competitive polytopal rearrangement. The planar structure of the intermediate detected upon thermo- and photoexcitation of the complexes was predicted from our calculations.     

Synthesis, structures, and properties of spiro[6-azaperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one derivatives

The reaction of 5-amino-4-chloroquinolines with 4-amino-2,6-di-tert-butylphenol yielded derivatives of spiro[6-azaperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one, which exhibit photo-and thermochromic properties in solutions. The structure of 2′,6′-di-tert-butyl-5,7,9-trimethylspiro[6-aza,-2,3-dihydroperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-one was established by X-ray diffraction study. The ring-chain isomerization of 2′,6′-di-tert-butyl-5,7-dimethyl-and 2′,6′-di-tert-butyl-5,7,8-trimethylspiro[6-aza-2,3-dihydroperimidine-2,4′-cyclohexa-2′,5′-dien]-1′-ones was studied by dynamic NMR spectroscopy. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2028–2034, November, 1997.     

Fast and reversible migrations of N,S-centered groups around the perimeter of cyclopropene and cycloheptatriene rings

The kinetics and mechanism of circumambulatory rearrangements of N-centered (NCS) and S-centered (SPh, SC₃Ph₃, SC(OEt)=S) groups in corresponding derivatives of 1,2,3-triphenylcyclopropene and cycloheptatriene were studied by dynamic¹H and¹³C NMR spectroscopy. Migrations of the isothiocyanate group occur by the dissociation-recombination mechanism with intermediate formation of a tight ionic pair. Migrations of the phenylthio group around the perimeter of cyclopropene and cycloheptatriene rings occur by the 1,2-shift mechanism. It was found that rearrangements of theO-ethyl dithiocarbonate group inS-(1,2,3-triphenylcyclopropen-3-yl)-O-ethyl dithiocarbonate occur by the 3,3-sigmatropic shift mechanism. The molecular and crystal structure ofO-ethylS-(1,2,3-triphenylcyclopropen-3-yl) dithiocarbonate was studied by X-ray analysis.     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

Photoinduced Acylotropic Rearrangement of Crown-Containing 2-[N-Acetyl-N-(4-aminobenzo-15-crown-5)methylene]-2,3-dihydrobenzo[b]thiophen-3-one

2-N-(4-Aminobenzo-15-crown-5)methylene-2,3-dihydrobenzo[b]thiophen-3-one and its acetyl derivative were synthesized. Their treatment with lithium, sodium, or potassium iodide in acetonitrile solution leads to formation of the corresponding crown-metal complexes. Irradiation of the acylated compounds at 436 nm induces NO migration of the acetyl group to give O-acyl isomer which is characterized by a considerable blue shift of the long-wave absorption band ( = 70 nm). The quantum yields of the photo- induced acylotropic reaction for the free ligand and its complexes with alkali metal cations change in the series: _L > K⁺ > Na⁺ > Li⁺.