Regio- and stereoselectivity in the hydrothiolation of alkynes with thiols in the presence of a variety of transition-metal catalysts is investigated in detail. Among the catalysts employed, RhCl(PPh3)3 exhibits excellent catalytic ability toward the anti-Markovnikov addition of thiols (ArSH) to alkynes (RC⋮CH), which affords the corresponding vinylic sulfides (trans-RCHCHSAr) regio- and stereoselectively. The reaction may proceed by the formation of hydrorhodium sulfide species (H−[Rh]−SAr) and probably via the subsequent hydrorhodation of alkynes to provide vinylrhodium intermediates (RCHCH−[Rh]−SAr). In contrast, PdCl2(PhCN)2-catalyzed hydrothiolation of aromatic alkynes (ArC⋮CH) takes place to give the corresponding Markovnikov adducts (R(ArS)CCH2) with excellent regioselectivity, probably via thiopalladation of alkynes by palladium sulfide species (ArS−[Pd]−Cl), which may be formed by ligand-exchange reaction between PdCl2(PhCN)2 and ArSH. Furthermore, in the case of alkynes bearing propargylic protons (R'CH2C⋮CH), a sequential addition/isomerization reaction occurs to provide the internal vinylic sulfides (R'CHC(SAr)CH3) regioselectively. From the same starting materials (alkyne and thiol), therefore, the regioselectivity of hydrothiolation can be attained simply by changing the catalysts, i.e., RhCl(PPh3)3 and PdCl2(PhCN)2.
Abstract Dialkyl arylphosphonates are prepared by the palladium-catalyzed reaction of aryl bromides with dialkyl phosphite in the presence of triethylamine. The similar treatment of vinyl bromides gives dialkyl vinylphosphonates stereoselectively.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxidative nucleophilic addition of organovanadium reagents to aldehydes with formation of ketonesToshikazu Hirao, Daisuke Misu, and Toshio AgawaCite this: J. Am. Chem. Soc. 1985, 107, 24, 7179–7181Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://doi.org/10.1021/ja00310a073RIGHTS & PERMISSIONSArticle Views1077Altmetric-Citations45LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (352 KB) Get e-Alerts Get e-Alerts
[1801-77-0] C2H5Cl2O2V (MW 182.91) InChI = 1/C2H5O.2ClH.O.V/c1-2-3;;;;/h2H2,1H3;2*1H;;/q-1;;;;+3/p-2/fC2H5O.2Cl.O.V/h;2*1h;;/qm;2*-1;;m/rC2H5Cl2O2V/c1-2-6-7(3,4)5/h2H2,1H3 InChIKey = DBFQWXKLCGFERX-PVPCXMFZCN (Lewis acid capable of one-electron oxidation; effects oxidative cleavage and oxidative coupling reactions) Physical Data: bp 32–34 °C/1 mmHg; yellow liquid;1 1.47 g cm−3. Solubility: sol most organic solvents such as alcohol, dichloromethane, hexane. Preparative Method: VO(OEt)Cl2 is prepared by addition of ethanol to Vanadyl Trichloride.2 Handling, Storage, and Precautions: moisture sensitive; should be handled under dry inert atmosphere and refrigerated in the dark to prevent decomposition (orange fumes). Avoid breathing the vapor; skin irritant and corrosive. Use in a fume hood.
Abstract Pyrrolochinolinchinon (PQQ) (I), das als Coenzym einiger Dehydrogenasen isoliert worden ist, katalysiert die Luft‐Oxidation von Cyclohexylamin zu Cyclohexanon.
The characterization of the iridium compounds bearing 2,3-diphenylquinoxaline units is presented here to afford vivid-red emitting phosphors with exceedingly high quantum yields and enhanced radiative transition performance. The series of 2,3-diphenylquinoxalinato-iridium phosphors are proposed to realize an efficient, bright and vivid-red emission.
The synthesis of 3-aryl-3-hydroxy-2-oxindoles, which are a structural motif found in various natural products and pharmaceutically active compounds, was conducted via reductive coupling of (2-aminophenyl)(aryl)methanone derivatives and CO2 as a key step. The conditions employing Mg with chlorotrimethylsilane in DMA are the best for the reductive coupling. The reductive coupling and acid-catalyzed lactam formation can be performed in a one-pot reaction to give the oxindoles.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
