Rearrangements in methanolysis of bis(2-bromoalkyl)selenides

Addition of selenium dibromide to 1-hexene, 1-octene, and allylic ethers occurs through the formation of intermediate kinetic anti-Markovnikov adducts that further transform into more thermodynamically stable Markovnikov adducts presumably via seleniranium intermediates. The methanolysis of both Markovnikov and anti-Markovnikov adducts leads to the formation of the same products in approximately the same ratio thus showing that the reaction proceeds through seleniranium intermediates.     

New reaction of 1H-pyrazoles with selenium dioxide: one-pot synthesis of bis(1H-pyrazol-4-yl)selenides

A novel reaction between 3- and 3,5-substituted pyrazoles with selenium dioxide proceeds with formation of bis(3R,5R′-1H-pyrazol-4-yl)selenides in high yield. On this basis, an efficient one-pot synthetic procedure has been developed. In the case of the unsubstituted pyrazole a selenonium compound has been obtained. The identity and structure of the isolated selenium derivatives have been confirmed by spectral methods and their molecular structures investigated by X-ray analysis.     

Synthesis and desilylation of some bis(trimethylsilyl)alkenes and polymers bearing bis(silyl)alkenyl groups

The synthesis of various vinylbis(silanes) from some aryl and heteroaryl aldehydes and (Me₃Si)₃CLi in Et₂O is described. Friedel-Crafts reaction of 1,1-bis(trimethylsilyl)-2-(2-naphthyl)ethene with various acyl chlorides (RCOCl, R = Me, Et, i-Pr, i-Bu, n-pent) gave the corresponding α-silyl-α,β-unsaturated enones with high E steroselectivity. Moreover, poly(styrene)-co-[2,2-bis(trimethylsilyl)ethenyl(styrene)] obtained via the reaction of polymers bearing pendant enone functions and (Me₃Si)₃CLi, reacts with the same acyl chlorides in the presence of catalytic amount of AlCl₃ to give the new macromolecules bearing α-silyl-α,β-unsaturated enones and α,β-unsaturated enones.     

A novel simple synthesis of bis(diorganoselenophosphoryl)selenides (R2PSe)2Se from secondary phosphines and elemental selenium

Secondary phosphines R₂PH [R = Ph(CH₂)₂, 4-t-BuC₆H₄(CH₂)₂, 4-MeOC₆H₄(CH₂)₂, 2-Naphth(CH₂)₂] react with two equivalents of elemental selenium under mild conditions (85 °C, 3 h, toluene) to afford bis(diorganoselenophosphoryl)selenides (R₂PSe)₂Se in high yields (75-92%).     

Synthesis and antimicrobial activity of arabinogalactan-stabilized selenium nanoparticles from sodium bis(2-phenylethyl)diselenophosphinate

Russian Chemical Bulletin - Water-soluble elemental selenium nanocomposites containing 0.8-3.9% Se were synthesized by oxidation of sodium bis(2-phenylethyl)diselenophosphinate in aqueous medium in...     

Hydrocarboxylation of terminal alkenes in supercritical carbon dioxide using perfluorinated surfactants

High selectivity in acids is obtained in the first example of hydrocarboxylation of 1-octene in supercritical carbon dioxide using a Pd/P(4-C6H4-CF3)3 catalyst system and a perfluorinated surfactant.     

Isotope effects and the mechanism of allylic hydroxylation of alkenes with selenium dioxide

The mechanism of the allylic oxidation of 2-methyl-2-butene with selenium dioxide was explored by a combination of experimental and theoretical studies. A comparison of the experimental (13)C and (2)H kinetic isotope effects with predicted values shows that the observed isotope effects are consistent with an initial concerted ene step mediated by SeO(2). However, this comparison also does not rule out the involvement of a selenous ester in the ene reaction or a stepwise reaction involving reversible electrophilic addition of HSeO(2)(+) followed by rate-limiting proton abstraction. Becke3LYP calculations strongly favor SeO(2) over a selenous ester as the active oxidant, with the predicted barrier for reaction of 2-methyl-2-butene with SeO(2) being 21-24 kcal/mol lower than that for reaction with H(2)SeO(3). The possibility of a selenous ester being the active oxidant is also disfavored by the observation of oxidations in non-hydroxylic solvents. The involvement of HSeO(2)(+) does not appear consistent with a lack of dependence of the reaction on the basicity of the reaction mixture. A concerted ene reaction with SeO(2) as the active oxidant appears to be the major mechanistic pathway operative in these reactions.     

Rearrangement of 4-(1-haloalkyl)- and 4-(2-haloalkyl)-2-azetidinones into methyl omega-alkylaminopentenoates via transient aziridines and azetidines

The synthesis of 4-(1-haloalkyl)-2-azetidinones and 4-(2-haloalkyl)-2-azetidinones was investigated with use of the Staudinger reaction between in situ generated ketenes and alpha-haloimines or beta-haloimines. This new class of functionalized 2-azetidinones was further evaluated for its potential use as intermediates in the synthesis of highly functionalized compounds. The reaction of 4-(1-haloalkyl)-2-azetidinones and 4-(2-haloalkyl)-2-azetidinones with sodium methoxide in methanol yielded ring-opened products, i.e., methyl 2-alkoxy-4-(alkylamino)pentenoate and methyl 5-(alkylamino)pentenoate, respectively. Further attention was paid in detail to the reaction mechanism involved in this peculiar transformation. It was proven that these reactions proceeded via intermediate aziridines or azetidines.     

Synthesis and structure of triphenylbismuth bis(2-phenylaminobenzoate)

Interaction of triphenylbismuth with phenylanthranilic acid in the presence of hydrogen peroxide yields triphenylbismuth bis(2-phenylaminobenzoate), in which bismuth atoms have a distorted trigonal bipyramidal coordination with phenyl ligands in equatorial positions. The bond lengths (Å) are as follows: Bi-C, 2.193(5), 2.200(4), and 2.200(4); Bi-O, 2.252(4) and 2.300(4). Intramolecular hydrogen bonds N-H?O(=C) (H?O, 1.91, 1.97 Å; N?O, 2.634(9), 2.667(9) Å) and donor-acceptor interactions Bi?O(=C) (2.790(5) and 2.838(5) Å) exist in the molecule.     

Cycloaddition of bis(trifluoromethyl)diazomethane to activated alkenes and alkynes

Bis(Trifluoromethyl)diazomethane undergoes [3+2] cycloaddition with activated alkenes and alkynes regiospecifically to give substituted pyrazolines and pyrazoles.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 452–455, February, 1992.     

Synthesis and characterization of bis(glycosylamino)benzenes based on reducing disaccharides

Synthesis of bis(glycosylamino)benzenes, derived from disaccharides lactose, maltose, and cellobiose, by direct condensation and their characterization are described. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1235–1238, May, 2005.     

Synthesis, structures and ab initio studies of selenium and tellurium bis(carbodithioates and carbothioates)

A series of selenium and tellurium bis(carbodithioates and carbothioates) were synthesized. X-Ray structure analysis revealed that Se(SSCC(6)H(4)OMe-2)(2), Te(SSCC(6)H(4)OMe-2)(2) and Te(SSCC(6)H(4)Me-4)(2) have trapezoidal-planar configuration of ES(4) (E = Se, Te) and despite the larger atomic radii, the C=S···Te distances in Te(SSCC(6)H(4)OMe-2)(2) are comparable to those in the corresponding selenium derivatives Se(SSCC(6)H(4)OMe-2)(2). Molecular-orbital calculations performed on compounds E(E'SCR)(2) (E = S, Se, Te; E' = O, S; R = Me, Ph, C(6)H(4)OMe-2) showed that the syn-conformers of Se(SSCR)(2) and Te(SSCR)(2) are more stable than the corresponding anti-ones, while, in the case of carbothioic acid derivatives, E(SOCR)(2) showed that their anti-conformers are all more stable than the corresponding syn-ones. Natural bond orbital (NBO) analyses of these dithio-compounds revealed that two types of orbital interactions, n(S(1))→σ*(E-S(2)) and n(O)→σ*(E-S(2)), play a role in the bonding of E[S(2)S(1)CC(6)H(4)OMe-2](2) (E = Se, Te) and the former play a particularly predominant role.     

Synthesis of P,B-containing heterocycles based on bis(α,2-dihydroxybenzyl)phenylphosphine

Conclusions Reaction of bis(,2-dihydroxybenzyl)phenylphosphine and its derivatives with the isobutyl ester of diphenylboric acid, the anhydride of phenylboric acid, and boric acid in the presence of amines forms ammonium 2,8,9-trioxa-1-borata-4-phospha-6,7-benzobicyclo[3.3.1] non-6-enes. Reaction with 2 equivalents of the isobutyl ester of diphenylboric acid gives bis(triethylammonium 2,2-diphenyl-5,6-benzo-1,3,2-dioxaborin-4-yl)phenylphosphine oxide.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 946–951, April, 1989.     

Synthesis of bis(glycosylamino)alkanes and bis(glycosylamino)arenes

The condensation of D-mannose and D-galactose with aliphatic and aromatic diamines afforded a series of bis(glycosylamino)alkanes and-arenes. A possible mechanism was proposed for the formation of 1,2-bis(β-D-glycosylamino)benzenes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2793–2801, December, 2005.     

The raman spectra of various bis(perfluoroethyl) sulphides,selenides, and tellurides

The vibrational spectra of (C₂F₅)₂S_x (x=2,3,4), (C₂F₅)₂Se_x (x=1,2,3), (C₂F₅)₂Te_x (x=1,2) and C₂F₅SeCl are reported and tentative assignments proposed.