A one-pot stereoselective synthesis of 1,4-dienyl selenides by hydrostannylation-Stille tandem reaction of acetylenic selenides with Bu_3SnH and allylic bromides

1,4-Dienyl selenides can be stereoselectively synthesized in one pot under mild conditions in good yields by the palladiumcatalyzed hydrostannylation of acetylenic selenides, followed by Stille coupling with allylic bromides.     

醋酸烯丙酯选择性地合成烯丙基硒醚

醋酸烯丙酯被Pd(PPh3)4-SmI2还原，并发生中间体π-烯丙基钯络合物的极性 反转，而后与芳基硒溴化物作用，生成烯丙基硒醚．     

Electron impact mass spectra of phosphine sulphides and selenides

An electron impact mass spectral study of phosphine sulphides and selenides established the effect of the heteroatom and the role of the ortho substituent in the fragmentation pattern.     

Synthesis of protected allylic amines from allylic phenyl selenides: Improved conditions for the chloramine T oxidation of allylic phenyl selenides

Anhydrous chloramine T in methanol is a highly effective reagent for the conversion of allylic phenyl selenides to the corresponding rearranged N-allylic-p-toluenesulfonamides. The reaction presumably proceeds via an allylic selenimide intermediate which undergoes [2,3]-sigmatropic rearrangement.     

Cross-coupling of aromatic bromides with allylic silanolate salts

The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85 degrees C in 1,2-dimethoxyethane with allylpalladium chloride dimer (2.5 mol %) to afford 73-95% yields of the allylation products. Both electron-rich and sterically hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (gamma-substitution) product. A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 40-83% yields. However, bromides containing coordinating groups (particularly in the ortho position) gave lower, and in one case even reversed, selectivity. Configurationally homogeneous (E)-silanolates gave slightly higher gamma-selectivity than the pure (Z)-silanolates. A unified mechanistic picture involving initial gamma-transmetalation followed by direct reductive elimination or sigma-pi isomerization can rationalize all of the observed trends.     

Asymmetric coupling of arylmagnesium bromides with allylic esters

Arylmagnesium bromides were allowed to react with 3-penten-2-yl (or 2-buten-1-yl) acetate (pivaloate, carbonate or methyl ether) in the presence of NiCl₂[(S, S)-Chiraphos] catalyst to afford (R)-4-aryl-2-pentene (or 3-aryl-1-butene) in high chemical and optical yields.     

Palladium-catalyzed reaction of allylic ammonium bromides with nucleophiles

The reactions of allylic triethylammonium bromides and dimethylsulfonium bromide with carbon nucleophiles were catalyzed by tetrakis(triphenylphosphine)palladium to afford olefinic esters and ketones.     

Reactions of halogenoquinolizinium bromides with diethylamine

The reactions of quinolizinium bromide (QB) and its four monobromo derivatives with diethylamine have been investigated. For Br in position 2 or 4, substitution is the main process, whereas for Br in positions 1 and 3 quantitative ring opening is found. The substituted pyridylbutadienes formed by ring opening, are cis-trans-butadienes, which isomerize into the all-trans forms. The steric cours of the ring opening is explained.     

Reactions of lithium tributyl heteroaryl borates with allylic bromides in the presence of copper(I) cyanide

The reaction of various lithium tributylheteroarylborates with allylic bromides in the presence of copper(I) cyanide furnished the regioselective allylation at the heteroaryl ring.     

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.     

Ni-catalyzed addition reaction of allylic selenides to alkynes

Nickel complex catalysts, Ni(cod)₂-2PPh₃ and Ni(cod)₂-dppb systems in particular, catalyze the addition reactions of phenyl allyl selenide to terminal alkynes to regioselectively afford 2-phenylseleno-1-allyl-1-alkenes in good to excellent yields. A mechanism that involves a η³-allyl-nickel complex is proposed on the basis of isolation, crystal structure determination and reactivity study of the complex.     

Reactions of halogenoquinolizinium bromides with aniline,isopropylamine and liquid ammonia

The reactions of quinolizinium bromide ( QB ) and its four monobromo derivatives with aniline, isopropylamine and liquid ammonia have been investigated. With aniline 2- and 4-bromo QB undergo substitution, whereas 1- and 3-bromo QB do not react at all. With liquid ammonia all bromo derivatives and the parent compound react with ring opening. This diversity in the reaction course is explained in terms of the HSAB principle. 2-BromoQB reacts with isopropylamine under formation of 2-isopropylamino QB . Two molecules of isopropylamine are involved in this substitution, as we isolated an intermediate: 1-isopropylamino-4(2-pyridyl)-3-isopropyliminio-1-butene bromide ( 13 ). The structure of the latter compound was confirmed by X-ray analysis.     

Ligating properties of tertiary phosphine/arsine sulphides or selenides. Part VII. Synthesis and characterisation of palladium(II) complexes with some mono- and ditertiary phosphine sulphides or selenides

Summary Palladium(II) halides react with triphenylphosphine sulphide or selenide, 1,1-methylenebis(diphenylphosphine sulphide or selenide) (MDPS or MDPSe), 1,3-trimethylene-bis-(diphenylphosphine selenide) (PDPSe) or tetramethyldiphosphine disulphide (TMDPS) forming complexes [PdBr₂ · 2L], [2PdBr₂ · 3L] (L=Ph₃PS or Ph₃PSe), [PdX₂ · L] (X=Cl, L =PDPSe; X=Br, L=MDPS or MDPSe; X=Cl or Br, L=TMDPS) and [3PdBr₂ · 2TMDPS]. Characterisation and stereochemical assignments have been made through elemental analyses, i.r., far i.r. and electronic spectra, magnetic susceptibility and molar conductance data and tga studies. Bidentate ligand complexes have higher thermal stability than the monodentate ligand complexes. Chelation or bridging modes of the bidentate ligands have been demonstrated.     

Reactions of sulphides in molten cryolite

The freezing point depression of cryolite (Na₃AlF₆) by the addition of Al₂S₃ and FeS was investigated. It was found that for contents of up to 10 wt.% Al₂S₃, it brings into the melt three new species. X-ray analysis of solidified melts of the system Na₃AlF₆–Al₂S₃ showed that it contained chiolite, Na₅Al₃F₁₄ and Na₂S. Chiolite originates from a reaction between Na₃AlF₆ and AlF₃. This suggests that the system Na₃AlF₆–Al₂S₃ is a part of the reciprocal system NaF, AlF₃//Na₂S, Al₂S₃. The solubility of FeS in cryolite melt is so low that it cannot be determined by the thermal analysis. When FeO is added to the Na₃AlF₆–Al₂S₃ melt, Fe²⁺ cations and S²⁻ anions react under the formation of solid FeS. A similar reaction was observed for Ni²⁺ and S²⁻ ions.     

Reactions of selenium bromides with butyl vinyl ether

Russian Journal of Organic Chemistry -     

Indium-mediated one-pot three-component reaction of aromatic amines, enol ethers, and allylic bromides

[reaction: see text] A new and efficient indium-mediated one-pot three-component reaction for the synthesis of N-aryl-substituted homoallylamines from aromatic amines, enol ethers, and allylic bromides in THF at room temperature is described.     

Synthesis of propargylic and allylic trifluoromethyl selenoethers by copper-mediated trifluoromethylselenolation of propargylic chlorides and allylic bromides

The copper-mediated trifluoromethylselenolation of propargylic chlorides and allylic bromides is described. This approach provides a wide range of propargylic and allylic trifluoromethyl selenoethers in moderate to good yields. These results open the way to synthesis strategies for various trifluoromethylselenolated compounds.     

Nickel-catalyzed reductive coupling of aryl halides with secondary alkyl bromides and allylic acetate

A room-temperature Ni-catalyzed reductive method for the coupling of aryl bromides with secondary alkyl bromides has been developed, providing C(sp(2))-C(sp(3)) products in good to excellent yields. Slight modification of this protocol allows efficient coupling of activated aryl chlorides with cyclohexyl bromide and aryl bromides with allylic acetate.     

Laser ablation synthesis of phosphorus sulphides, selenides and ternary Pp Sq Ser clusters from various precursors

Laser ablation (LA) synthesis with simultaneous time-of-flight mass spectrometric (TOF MS) analysis was used to examine the formation and composition of ternary Pp Sq Ser clusters. Clusters formed by LA of various precursors are singular, binary and ternary. Formation of negative or positive singly charged Pp, Sq and Ser clusters, where Pp + (p = 1-249), Pp* (p = 1-191), Sq* (q = 1-15), Sq + (q = 1-12), Ser* (r = 1-8) and Ser+ (r = 1-9), was identified. High numbers of binary Pp Sq, Sq Ser (35) or ternary Pp Sq Ser (138) clusters were formed by LA synthesis from the various mixtures. Most of the ternary Pp Sq Ser clusters were formed either from a mixture of P4S3 with selenium (grey) or from a mixture of SeS2 with red phosphorus. In total, 138 new ternary Pp Sq Ser clusters were identified. The conditions for the formation of such possible prospective nano-materials are given.