The role of electronic factors in reagents in controlling thestereochemistry of arylsulfenyl chlorides addition

For a series of substituted arylsulfenyl chlorides the stereochemistry of Ad_E-reactions with a series of substituted Z- and E-β-deuterostyrenes has been elucidated. Non-stereospecific reaction was observed only for the pair 2,4-dinitrobenzenesulfenyl chloride-p-methoxystyrene; for all the other reactants the reaction proceeded in a strictly stereospecific manner.     

Kinetic Analysis of the Mechanism of Oxidation of CO on Co/ZSM-5

We have studied the kinetic behavior of oxidation of carbon monoxide on Co-containing zeolite ZSM-5. We have shown that the kinetic curves obtained for the dependence of the reaction rate on the reagent concentration can be described by an Eley–Rideal mechanism, which assumes that oxygen can be adsorbed on the surface of the catalyst in both atomic and molecular form, followed by reaction of CO from the gas phase with the adsorbed oxygen.     

Synthesis,molecular structure,and absolute configuration of 1-α-pheitylethyl-3-(2-cyanoethyl)-4-piperidone

The Michael addition of acrylonitrile to the pyrrolidine enamine of 1-(S--phenyl-ethyl)-4-piperidone proceeds with the formation of. a 1:1 mixture of l-(S--phenyl ethyl)-3-(2-cyanoethyl)-4-piperidone diastereomers. A diastereomer isolated in pure form was shown by x-ray diffraction structural analysis to have S-configuration of the new chiral center at C₍₃₎ of the piperidone ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp, 1656–1662, December, 1985.     

Adducts of vinyl ethers with arylsulfenyl chlorides as reagents for electrophilic alkylation of vinyl ethers

Conclusions A general preparative method for the chemically selective codimerization of vinyl ethers has been developed, the first stage of which is addition of arylsulfenyl chloride to one vinyl ether and the second is an Ad_E reaction between the adduct obtained and the other vinyl ether in the presence of a Lewis acid followed by treatment of the intermediate with some nucleophile.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 119–125, January, 1987.     

Chiral ditopic receptors. Application to palladium-catalyzed allylic alkylation

Chiral pyridinooxazoline, quinolinooxazoline, bis(oxazolino)pyridine (pybox), and bisoxazoline (box) derivatives containing crown ether residues were prepared. Some of the ligands were assessed in substrate binding studies and in palladium catalyzed allylic alkylations.     

Electronic effects in the cyclopentadienyl ring. The 13C NMR spectraof monosubstituted ferrocenes

The chemical shifts of C(2,5) and C(3,4) carbons in the ¹³C NMR spectra of monosubstituted ferrocenes have been assigned using deuterium labelling. An analogy is observed between the shielding of C(2,5) and C(3,4) carbons of ferrocene derivatives and ortho- and para-carbons of benzene derivatives withthe same substituents. Electron-density distribution in the cyclopentadienyl ring is discussed on the basis of ¹³C NMR data.     

Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and Their Benzene Solvates: EPR and Solid-State Natural Abundance (13C, 15N) CP/MAS NMR

Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)₂], and their benzene solvates [M(Py)(Mdtc)₂] · 0.5C₆H₆ were synthesized. The electron paramagnetic resonance method and solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)₂], and in its solvate, [Cu(Py)(Mdtc)₂] · 0.5C₆H₆ is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)₂]. In the solvated adduct [Cu(Py)(Mdtc)₂] · 0.5C₆H₆, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)₂] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc^–ligands in [Zn(Py)(Mdtc)₂] · 0.5C₆H₆. Signals in the ¹⁵N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn₂(Mdtc)₄] species is accompanied by the dissociation of binuclear molecules.     

Amidine tautomerism in the 1,3-diacyl-2-(5-substituted furfuryl)thiourea series. Molecular structure of 1,3-diacetyl-2-(5-ethoxycarbonylfurfuryl)thiourea

The effect of substituents in the furan ring on the dynamics of amidine tautomerism in 1,3-diacetyl-2-(5-R-furfuryl)thioureas is demonstrated. The conformation of 1,3-diacetyl-2-(5-ethoxycarbonylfurfuryl)thiourea was established by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 741–745, June, 1991.