Salt effects and the mechanism of electrophilic mercuration of unsaturated compounds

The reaction of Hg(OAc)₂ with bornylene in THF-H₂O and CH₃CN-H₂O mixed solvents (75 25, v/v) was studied. The effects of the addition of NaOAc on the reaction rate and the composition of products were investigated. In the CH₃CN-H₂O mixture, the addition of NaOAc decreases the amount of the rearranged product, fundamentally changes the ratio between the regioisomeric solvoadducts, and promotes the formation of products of Hg(OAc)₂ addition. The reaction proceedsvia an ion pair and free mercurinium ion; the cation of the ion pair and the free mercurinium ion have dissimilar structures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 544–548, March, 1995.     

New homochiralortho-palladated matrix bearing a bulky substituent at the carbon stereocenter

A new homochiral dimericortho-palladated complex bearing a bulkytert-butyl substituent at the carbon stereocenter was synthesized from optically activeN,N-dimethyl-α-tert-butylbenzylamine. Regioselective activation of only the aromatic C−H bond was shown to occur during the cyclometallation process proceeding under very mild conditions due to steric effects. Spectral characteristics of mononuclear derivatives of the new dimeric complex indicate that the five-membered palladacycle exists predominantly in one of two possible chiral conformations with the axial position of thetert-butyl substituent. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1375–1384, July, 1997.     

Sterically hindered aliphatic amines in the controlled synthesis of polystyrene

The kinetic features of radical polymerization of styrene in the presence of primary and secondary aliphatic amines combined with benzoyl peroxide and the molecular-mass characteristics of the resulting polymers were studied. In the presence of peroxide initiators, aliphatic amines, as potential sources of stable aminoxyl radicals, provide the synthesis of polystyrene with a controlled molecular mass without gel effect at a relatively high rate. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 159–164, January, 2007.     

Indole fulgides

The syntheses and photochemical properties of fulgides derived from indole and indoline are reviewed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–753, June, 1992.     

Novel ruthenium(ii) and (iii) carborane complexes with diphosphine ligands and their application in radical polymerization

Ruthenium(ii) and (iii) carborane complexes containing XantPhos as a ligand were synthesized for the first time. It was shown that the reaction of the known complex exo-5,6,10-[Cl(Ph₃P)₂Ru]-5,6,10-(µ-H)₃-10-H-nido-7,8-C₂B₉H₈ with a 10% molar excess of XantPhos in benzene at 80 °C leads to a new closo-ruthenacarborane 3-Cl-3,3-[x²-XantPhos]-closo-3,1,2-RuC₂B9H₁₁, which can be easily converted to the corresponding acetonitrile complex 3-CH₃CN-3,3-[x²-XantPhos]-closo-3,1,2-RuC₂B₉H₁₁ by the reaction with isopropylamine in a dichloromethane—acetonitrile solvent mixture at 40 °C. These compounds, as well as previously synthesized ruthenium(ii) carborane complexes, were used as a basis for new catalyst systems allowing to conduct controlled radical polymerization at high rates even at low catalyst loading. The specific features of methyl methacrylate polymerization under the action of the indicated catalyst systems were considered and the mechanism of the process was investigated.

     

Mechanism of the photoreactions of fulgides based on 1,2-dimethyl-3-formylindole

Only E Z isomerization is observed for the steady irradiation of fulgides based on 1,2-dimethyl-3-formylindole in contrast to the analogs based on 3-acetylindole. The formation of cyclic photoisomers is registered by the method of impulse photolysis. The presence of a methyl substituent in the position 2 of the indole portion leads to a significant increase in the stability of the photochromic system. The introduction of alternative reaction centers of cyclization in the form of bulky phenyl groups leads to the suppression of electrocyclization at the position 2 of the indole portion and the formation of dihydronaphthalene structures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1255–1258, September, 1991.     

Synthesis of poly(N-vinylpyrrolidone) and N-vinylpyrrolidone-methyl methacrylate copolymers in the presence of C-phenyl-N-tert-butylnitrone

The free-radical polymerization of N-vinylpyrrolidone and its copolymerization with methyl methacrylate have been studied at 60°C in the presence of C-phenyl-N-tert-butylnitrone as a chain-growth regulator. It has been shown that the above additive makes it possible to synthesize poly(N-vinylpyrrolidone) and its copolymers without any gel effect and to control molecular-mass characteristics of homo-and (co)polymers.     

Features of acrylonitrile radical polymerization in the presence of iron carbonyl complexes

It was shown that mono- and binuclear carbonyl complexes combined with carbon tetrachloride were effective initiators of the radical polymerization of acrylonitrile. The mechanism of initiation of acrylonitrile polymerization in the presence of the investigated iron complexes was studied.