- EFFICIENT AND/OR SELECTIVE METHYLATION BY DIAZOMETHANE OF ALCOHOLS, HALO ALCOHOLS, GLYCOLS, AMINO ALCOHOLS AND MERCAPTO ALCOHOLS WITH THE USE OF A PROTON-EXCHANGED X-TYPE ZEOLITE AS AN ACID-BASE BIFUNCTIONAL CATALYST
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Reactions of diazomethane with butanol, allyl alcohol and β- and γ-halo alcohols led to efficient methylation (giving the corresponding methyl ethers) with the use of a proton-excahnged X-type zeolite compared with H2SO4.The reactions with propylene and isobutylene glycols using the zeolite provided regioselective methylation of the primary OH rather than the secondary or tertiary OH, whereas regioselectivity was not observed in the reactions using H2SO4.The reactions with 2-aminoethanol and 2-mercaptoethanol showed high chemoselective S-methylation and N-monomethylation, respectively, in the presence of the zeolite instead of H2SO4.The mechanism for the reactions is proposed to involve acid-base bifunctional catalysis of the zeolite in which the acidic site reacts with diazomethane to form its conjugate acid, and the nucleophilicity of OH and SH groups is enhanced by the interaction of the basic site with the proton of the groups.
- Takeuchi, Hiroshi,Kishioka, Hiroaki,Kitajima, Kunio
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- Matrix isolation and spectroscopic properties of the methylsulfinyl radical CH3(O)S
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The atmospherically highly relevant methylsulfinyl radical CH 3(O)S was generated thermally under flash pyrolysis conditions and isolated in Ar matrices at 10 K; the allyl radical is a byproduct. CH 3(O)S and its D3- and 13C-isotopologues were characterized through the excellent agreement between experimental and computed IR and UV/Vis spectra.
- Reisenauer, Hans Peter,Romanski, Jaroslaw,Mloston, Grzegorz,Schreiner, Peter R.
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Read Online
- Yb(iii)-catalysedsyn-thioallylation of ynamides
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Reported herein is asyn-thioallylation of ynamides incorporating a sulfide moiety at the α-position and an allyl group at the β-position of the ynamide. The transformation is successful under ytterbium(iii)-catalysis, providing access to highly substituted thioamino-skipped-dienes with broad substrate scope. Thus, tetrasubstituted olefins (with four different functional groups: amide, phenyl, thioaryl/alkyl, and allyl on the carbon centers) are made in a single step from readily accessible ynamides, preserving complete atom economy. The reaction can be extended to the synthesis of selenoamino dienes by ynamidesyn-selenoallylation. DFT studies and control experiments provide insight into the reaction mechanism.
- Dutta, Shubham,Gandon, Vincent,Gogoi, Manash Protim,Mallick, Rajendra K.,Prabagar, B.,Sahoo, Akhila K.,Vanjari, Rajeshwer,Yang, Shengwen
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supporting information
p. 7521 - 7524
(2021/08/05)
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- Aqueous hemin catalyzed sulfonium ylide formation and subsequent [2,3]-sigmatropic rearrangements
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A mild hemin catalytic system for sulfonium ylide generation via a metal carbenoid and a subsequent [2,3]-sigmatropic rearrangement reaction in aqueous solvent is well-established, with the assistance of cyclodextrin (CD) and Triton X-100. The protocol displays high catalytic activity with a broad substrate scope of aryl/alkyl allyl sulfides and diazo reagents, affording homoallyl sulfide products in up to 99% yield. Notably, this catalytic system is successful for water-insoluble allyl sulfides but ineffective for allyl amines or allyl ethers. Moreover, an unprecedented cascade reaction of sulfonium ylide formation, [2,3]-sigmatropic rearrangement and C-H insertion was reported.
- Xu, Xiaofei,Li, Chang,Tao, Zhihao,Pan, Yuanjiang
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supporting information
p. 1245 - 1249
(2017/08/15)
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- Using CS2 to Probe the Mechanistic Details of Decarboxylation of Bis(phosphinite)-Ligated Nickel Pincer Formate Complexes
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The reaction of the formate complex {2,6-(R2PO)2C6H3}Ni(OCHO) (R = tBu, 5; R = iPr, 6) with CS2 shows first-order kinetics in nickel concentration and zero-order in [CS2/su
- Ma, Qiang-Qiang,Liu, Ting,Adhikary, Anubendu,Zhang, Jie,Krause, Jeanette A.,Guan, Hairong
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p. 4077 - 4082
(2017/01/10)
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- Reactions of 2-(α-Haloalkyl)thiiranes with nucleophilic reagents: V.* Reactions of 2-(α-chloroalkyl)thiiranes with organolithium compounds
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2-(α-Haloalkyl)thiiranes reacted with methyl-, butyl-, and phenyllithium to give the corresponding allyl sulfides. The reactions of diastereoisomeric erythro-and threo-2-(1-chloroethyl)thiiranes with phenyllithium were stereospecific, and they afforded (E)-and (Z)-1-phenylsulfanylbut-2-enes, respectively. 3-Chloromethyl-2,2- dimethylthiirane and phenyllithium gave rise to a mixture of 3-methyl-3-phenylsulfanylbut-1-ene and 3-methyl-1-phenylsulfanylbut-2-ene. The reactions of 2-chloromethylthiiranes with phenyllithium and methyllithium in the presence of a catalytic amount of copper(I) iodide (10 mol %) led to the formation of substituted thiiranes as the major products. Mechanisms of the observed transformations are discussed. Pleiades Publishing, Ltd., 2010.
- Tomashevskii,Sokolov,Potekhin
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experimental part
p. 1822 - 1825
(2011/04/17)
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- INTEGRIN MODULATORS AND METHODS FOR THEIR USE
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1,5-Dithiaocta-2,7-diene-5-oxide-1-yl(DODOyl) compounds and derivatives thereof, referred to collectively as DODOyl-derived compounds (DDCs), and chiral enantiomers and derivatives thereof, are described, which are integrin modulators that modulate integrin-mediated functions and/or processes. Pharmaceutical compositions containing integrin modulators and chiral enantiomers thereof, and methods for using integrin modulators and chiral enantiomers thereof are further described.
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Page/Page column 56
(2008/06/13)
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- Antiviral composition derived from allium CEPA and therapeutic use thereof
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Novel medicinal extracts derived from Allium species, preferablyAllium cepaare provided. These extracts have broad medicinal properties, especially for treatment of AIDS and other viral infections.
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- Isomerization processes in the synthesis of asymmetric allyl chalcogenides
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Allyl-propenyl rearrangement (prototropic isomerization) occurs in the synthesis of allyl organyl chalcogenides in a hydrazine hydrate - KOH system with a 6 - 10-fold molar excess of KOH. Specificities of the rearrangement that depend on the nature of the chalcogen were studied.
- Deryagina,Korchevin
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p. 223 - 225
(2007/10/03)
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- Structure-Stability Relationships in Vinyl Sulfides. III. Stabilization Caused by Different Alkylthio and Phenylthio Groups Attached to an Olefinic Double Bond
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The stabilization energies of different alkylthio and phenylthio groups attached to an olefinic double bond have been evaluated with respect to the energy differences of the isomerization reactions of some unsaturated sulfides, in which the double bond migrates from the β,γ- to the α,β-position.According to these results the stabilization energies (in kJ mol-1) are: MeS 15.6, EtS 14.8, i-PrS 15.7, t-BuS 17.5 and PhS 14.4
- Kimmelma, Reijo
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p. 550 - 555
(2007/10/02)
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- NEW REDUCTION OF SULFOXIDES AND SULFILIMINES TO SULFIDES WITH ZINC/1,4-DIBROMOBUTANE. A PROPOSAL FOR A RADICAL-FORMING ELECTRON TRANSFER PROCESS
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Based upon (13)C NMR spectroscopic observations of the deuteriorated methylcyclopropane and 1-butene, a bromoalkyl radical process has been considered in the reduction of sulfoxides and sulfilimines to sulfides by zinc/1,4-dibromobutane.KEYWORDS --- sulfide; reduction; sulfoxide; sulfilimine; zinc; 1,4-dibromobutane; single electron transfer; (13)C NMR; deuterio-methylcyclopropane; deuterio-butene-1
- Nagasawa, Kazuo,Yoneta, Akemi,Sugimoto, Hideki,Ito, Keiichi
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p. 4351 - 4354
(2007/10/02)
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- Homogenous Catalysis. Production of Allyl Alkyl Sulphides by Palladium Mediated Allylation
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The use of O-allyl S-alkyl dithiocarbonate substrates in palladium mediated catalytic allylation gives carbonyl sulphide and allyl alkyl sulphides with net retention of configuration and their use obviates the problems associated with sulphur nucleophiles in catalytic allylation.
- Auburn, Pamela R.,Whelan, John,Bosnich, B.
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p. 146 - 147
(2007/10/02)
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