Synthesis of 1,2-bis(methoxyamino)cycloalkanes from alicyclic 1,2-bis(hydroxyamines)

Derivatives of 1,4-dihydroxypiperazine-2,3-dione were obtained by reaction of cis-1,2-bis(hydroxyamino)cycloalkanes with diethyl oxalate. Their alkylation with CH₂N₂ or Mel afforded 1,4-dimethoxypiperazine-2,3-diones. Hydrolysis of the latter gave 1,2-bis(methoxyamino)cycloalkanes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 925–929, April, 1996.     

A comparative quantum-chemical analysis of electronic structures and spectroscopic parameters of cycloalkanes and cyclopolysilanes

A comparative quantum-chemical analysis of the electronic structures and spectroscopic parameters of the cycloalkanes C₃H₆, C₄H₈, C₅H₁₀, and C₆H₁₂ and their silicon analogs Si₃H₆, Si₄H₈, Si₅H₁₀ and Si₆H₁₂ was performed in the framework of the SCF MO LCAO method in the INDO approximation. Qualitative interpretation of “abnormal” ionization potentials and energies of electronic absorption spectra of cyclopolysilanes has been given. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1105–1108, June, 1997.     

The kinetics of hydroxyl radical reactions with cyclopropane and cyclobutane

A laser flash photolysis/resonance fluorescence investigation has been carried out to study the kinetics of the overall reactions OH + cyclopropane (1) and OH + cyclobutane (2) in the temperature range 298–490 K and at 298 K, respectively. The following kinetic parameters have been determined: k₁ =(3.9 ±0.6) 10⁻¹²exp- (2.2 ± 0.1)kcal mol⁻¹/RT molecule⁻¹cm³s⁻¹, k₂(298 K) = (17.5 ± 1.5)10⁻¹³molecule⁻¹ cm³s⁻¹.     

Multigram Synthesis of α- and γ-((Hetera)cyclo)alkylpyridines through α-Arylation of (Hetero)aliphatic Nitriles

A systematic study on the S_nAr reaction of halogenated fluoropyridines and (hetero)aliphatic nitrile anions as an approach to the synthesis of functionalized pyridines bearing a (cyclo)alkyl or saturated heterocyclic substituent by is described. The scope of the method was demonstrated on a wide range of (hetero)aliphatic nitriles (including three- to six-membered cycloalkane derivatives and N-, O-, S-containing saturated heterocycles) and all isomeric halogenated 2-and 4-fluoropyridines. High chemo- and regioselectivity (i. e., exclusive substitution of the fluorine atom), as well as excellent scalability of the proposed reaction sequence were demonstrated (up to 450 g for the arylation step or up to 77 g of cycloalkylpyridine over two steps in a single run). The utility of the synthesized products was illustrated in the additional functional group transformations resulting in synthetically valuable pyridine-containing building blocks.     

Polyhalomethanes combined with aluminum halides in one-step syntheses of carbonyl-containing compounds from alkanes and cycloalkanes

Data on new-generation superelectrophiles containing polyhalomethanes and aluminum halides are generalized. These systems open up broad prospects for organic syntheses based on alkanes and cycloalkanes. With these systems, reactions of various alkanes and cycloalkanes with CO were performed for the first time. Superelectrophiles underlay the development of new one-pot methods for the synthesis of carbonyl-containing compounds of various classes from readily available alkanes (or cycloalkanes) and CO. The reactions are usually selective and give the target products in high yields.     

Temperature‐dependent conformational analysis of cyclononane: An ab initio study

Quantum chemical methods were used for the theoretical determination of the conformational population for the relevant conformers of cyclononane, i.e., TBC, TCB, TCC, and M4 (or C1), which have been previously investigated experimentally through detailed examination of the nuclear magnetic resonance (NMR) spectrum. Our best Gibbs free energy result, evaluated with MP4(SDTQ)/6‐31G(d,p)//MP2/6‐31G(d,p) energy differences and MP2/6‐31G(d,p) thermal corrections, lead to a temperature‐dependent population in excellent agreement with the experimental results based on the analysis of the low temperature ¹³C NMR spectrum. The nice agreement with experiment is achieved using MP2 harmonic frequencies for the evaluation of vibration partition functions within the standard statistic thermodynamics formalism. Theoretical temperature‐dependent infrared (IR) and ¹³C NMR spectra were simulated and compared with experimental data, which confirmed the ab initio conformational population reported here. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

The FeII-FeIV and FeIII-FeV manifolds in an expanded world of Gif chemistry

The Gif systems for the selective functionalization of saturated hydrocarbons based on the reactions of Superoxide with Fe^II and of hydrogen peroxide with Fe^III are described. Both systems are relatively efficient, but not nearly so efficient as the electrochemical system developed in collaboration with Prof. G. Balavoine and Dr. Aurore Gref (Université de Paris-Sud-Orsay, France). All of the systems afford mainly ketones. This is an unusual selectivity, which implies a non-radical mechanism. It has been proven for the Fe^III-H₂O₂ system that the activation of the Fe^III is independent of the formation of ketone, which involves a hydroperoxide (derived from oxygen) as an intermediate. This intermediate controls the formation of ketone and of secondary alcohol. The addition of a number of trapping reagents such as BrCCl₃ diverts the reaction from oxygenation to bromide formation. Although BrCCl₃ is indeed a good trap for carbon radicals, the pattern of selectivity across a range of saturated hydrocarbons is completely different for Gif chemistry when compared with normal radical bromination. The chemistry is explained in terms of an Fe^V oxenoid species that inserts itself into secondary C-H bonds (a compromise between bond strength and steric hindrance). This gives an Fe^V intermediateA with an iron-carbon bond, which is probably rapidly reduced to the Fe^III state by hydrogen peroxide. Then oxygen is inserted into the Fe^III-C bond. Hydrolysis affords the isolateable intermediate hydroperoxide (intermediateB). A system based ontert-butyl hydroperoxide (TBHP) is described. This is similar to the above Gif systems, but the kinetic isotope effect is very different and the selectivity for adamantane substitution is different. However, Fe^III is activated by TBHP to an Fe^V oxenoid which, after reaction with a hydrocarbon, reacts with oxygen to give a hydroperoxide. So the pattern of intermediatesA andB is maintained with TBHP. Radical chemistry is involved in some of the reactions that involve ionic coupling to saturated hydrocarbons. The importance of the Fe^II-Fe^IV manifold in providing a mechanism that permits the selective functionalization of saturated hydrocarbons by ionic trapping with chloride, azide, and other anions is made manifest. Comparison is made with the Fe^III-Fe^V manifold where ionic trapping is never seen. Traditional Fenton chemistry (hydroxyl radical formation) is not operative here, but the trapping does involve the formation of carbon radicals. These react very efficiently with anions bonded to Fe^III.D. R. H. Barton is a Nobel Prize winner in chemistry in 1969. Since 1994, he is a foreign member of the Russian Academy of Sciences.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 595–604, April, 1995.We thank all our colleagues cited in the various References for their contributions to this fascinating subject. We also thank Prof. Minisci for his helpful comments. This work was supported by Quest Intl. and by the Welch Foundation.     

Synthesis and transformations of metallocycles

A novel regio- and stereoselective method for synthesizingthreo-2,3-disubstituted 1,4-dialumobutanes from -olefins and haloalanes (Et₂AlCl, (Et₂N)₂AlCl, (EtO)₂AlCl, Bu _i ² AlCl) with the participation of catalytic amounts of Cp₂ZrCl₂ or ZrCl₄ in the presence of magnesium metal was developed. The products of hydrolysis and deuterolysis of the dialuminum compounds obtained have athreo-configuration. The selective transformations of 1,4-dialumobutanes totrans-3,4-disubstituted tetrahydrothiophenes,trans-1,2-disubstituted cyclobutanes, and disubstituted ,-dienes were found to be possible.For Part 15, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1561–1567, August, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 93-03-04136).