The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Yongmin Zhang - One of the best experts on this subject based on the ideXlab platform.
-
New progress in the application of Samarium reagent to organic synthesis
2020Co-Authors: Yongmin ZhangAbstract:The recent studies of our group on the application of Samarium reagent to organic synthesis were reviewed in this paper, which mainly include the following contents: (1) studies on organic reactions promoted by Samarium diiodide; (2) the direct use of metallic Samarium in organic synthesis; (3) the application of other Samarium reagent such as Samarium triiodide and organoSamarium (allyl Samarium bromide) to organic reactions.
-
CeCl3/Sm induced reductive cleavage of the S-S bond in disulfide : A novel method for the synthesis of β-thioesters, thiol-esters and alkylphenyl sulfides
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry, 2005Co-Authors: Xue Li, Songlin Zhang, Yongmin ZhangAbstract:Disulfide has been reduced by cerium trichloride and Samarium in tetrahydrofuran to produce Samarium thiolates. The "living" species reacts smoothly with α,β-unsaturated esters(nitriles) to afford β-thioesters(nitrile) under mild and neutral conditions. The new thiolate anion also reacts with acyl halides, anhydrides and alkyl or benzyl halides to give thioesters and sulfides, respectively.
-
Synthesis of 1,3-diaryl-3-aminopropynes via the dethiolation of thioamides promoted by the Samarium/Samarium diiodide mixed reagent
Journal of Chemical Research-s, 2005Co-Authors: Weixing Qian, Yongmin ZhangAbstract:Promoted by the Samarium/Samarium diiodide mixed reagent, the C-H insertion of phenyl acetylene via the dethiolation of N,N-disubstituted aromatic thioamides was successfully performed to afford 1,3-diaryl-3-aminopropynesin good yields.
-
A novel stereospecific aminocyclopropanation via the dethiolation of thioamides promoted by the Samarium/Samarium diiodide mixed reagent
Journal of Chemical Research-s, 2005Co-Authors: Weixing Qian, Yongmin ZhangAbstract:The stereospecific aminocyclopropanation of styrene via the dethiolation of N,N-disubstituted aromatic thioamides promoted by the Samarium/Samarium diiodide mixed reagent has been successfully performed.
-
Facile Formation of Samarium (III) Selenolates From Potassium Iodide Catalyzed Reaction of Samarium Metal and Diselenides, and Their Application in Synthesis of Selenoesters
Synthetic Communications, 1999Co-Authors: Genliang Lu, Yongmin ZhangAbstract:Abstract Samarium metal reacts with diselenides in the presence of a catalytic amount of potassium iodide to generate Samarium(II1) selenolates. Samarium (111) selenolates thus formed in situ, react with acid chlorides to give selenoesters in moderate yields.
M. L. Kaul - One of the best experts on this subject based on the ideXlab platform.
-
Thermal behaviour of gel-grown pure and mixed rare earth tartrates of yttrium and Samarium
Bulletin of Materials Science, 1997Co-Authors: Anima Jain, M. L. Kaul, Sushma Bhat, Sanjay Pandita, P. N. KotruAbstract:Thermal behaviour of gel-grown pure and mixed rare earth tartrates of yttrium and Samarium is investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal behaviour suggests that the materials are unstable at lower energies and pass through various stages of decomposition, decomposing to respective rare earth oxides which remain stable on further heating. It is estimated that both pure yttrium and pure Samarium tartrate crystals carry eight waters of hydration, while mixed yttrium Samarium tartrate crystals carry six waters of hydration. Critical examination of TG and DSC curves shows that the initial decompositions are endothermic and the latter are exothermic. Thermal kinetics of these materials has been worked out using Horowitz-Metzger, Piloyan-Novikova and Coats-Redfern equations. Application of these equations to these materials yields values of activation energy, order of reaction and frequency factor which are in reasonably good agreement.
-
Characterization of gel-grown pure and mixed spherulitic crystals of yttrium and Samarium tartrates
Materials Chemistry and Physics, 1994Co-Authors: Anima Jain, P. N. Kotru, M. L. KaulAbstract:The results were obtained from X-Ray powder diffractograms, infrared spectra, and quantitative chemical analysis of gel-grown pure and mixed crystals of yttrium and Samarium tartrates. XRD results indicate the crystalline nature of these materials. IR spectra for these crystals show all the bands expected from metal tartrate with water of hydration. It is seen from the band assignments that each metal atom is coordinated with one-OH and one carboxylic group from a molecule of tartaric acid. It is established from carbon-hydrogen and metal analysis that the gel grown spherulitic yttrium and Samarium tartrate crystals contain eight waters of hydration while the mixed yttrium Samarium tartrate spherulitic crystals contain six waters of crystallization. The exact stoichiometries are Y2(C4H4O6)3· 8H2O, Sm2(C4H4O6)3· 8H4O and (Y1 2Sm1 22(C4H4O6)3· 6H2O. The 1:1 ratio of Y and Sm in mixed crystals is further confirmed by EDAX analysis. © 1994.
Carmen Concellon - One of the best experts on this subject based on the ideXlab platform.
-
stereospecific and highly stereoselective cyclopropanation reactions promoted by Samarium
Chemical Society Reviews, 2010Co-Authors: Jose M Concellon, Humberto Rodriguezsolla, Carmen ConcellonAbstract:Samarium metal and Samarium diiodide have become important tools as selective cyclopropanating agents in organic synthesis due to their high chemo- and stereoselectivity. Therefore, Sm and SmI2 are the ideal reagents to prepare cyclopropane derivatives. This tutorial review highlights C–C multiple bond cyclopropanation processes promoted by Samarium or Samarium diiodide.
Christine Beemelmanns - One of the best experts on this subject based on the ideXlab platform.
-
towards the core structure of strychnos alkaloids using Samarium diiodide induced reactions of indole derivatives
Chemistry: A European Journal, 2013Co-Authors: Christine Beemelmanns, Steffen Gross, Hansulrich ReissigAbstract:This report describes the development of a first and second generation approach towards the synthesis of the ABCEG pentacyclic core structure of Strychnos alkaloids. First, we discuss a sequential approach applying a series of functional group transformations to prepare suitable precursors for cyclization reactions. These include attempts of Samarium diiodide-induced cyclizations or a Barbier-type reaction of a transient lithium organyl, which successfully led to a tetracyclic key building block earlier used for the synthesis of strychnine. Secondly, we account our first steps towards the development of an atom-economical Samarium diiodide-induced cascade reaction using “dimeric” indolyl ketones as cyclization precursors. In this context, we discuss plausible mechanisms for the Samarium diiodide-induced cascade reaction as well as transformations of the obtained tetracyclic dihydroindoline derivatives.
-
Samarium diiodide induced ketyl het arene cyclisations towards novel n heterocycles
Chemical Society Reviews, 2011Co-Authors: Christine Beemelmanns, Hansulrich ReissigAbstract:In this tutorial review we discuss recent advances in the field of ketyl-(het)arene cyclisations promoted by Samarium diiodide and related processes. Couplings of Samarium ketyls with carbon–carbon multiple bonds are perhaps the most useful reactions to create carbocycles and heterocycles of various ring sizes. They have also successfully been exploited for the synthesis of biologically active compounds or natural products. In this article we intend to summarise our diversity orientated approaches towards nitrogen heterocycles and emphasize other approaches with SmI2 as well as electrochemical cyclisation methods providing similar N-heterocycles. We also briefly discuss our recently published formal total synthesis of strychnine employing a new Samarium diiodide induced cascade reaction as key step. All these examples demonstrate the high synthetic potential of Samarium ketyl-(het)arene cyclisations for the preparation of various types of important heterocyclic compounds.
-
New Samarium diiodide-induced cyclizations
Pure and Applied Chemistry, 2011Co-Authors: Christine Beemelmanns, Hansulrich ReissigAbstract:Samarium diiodide (SmI 2 ) smoothly promotes the cyclizations of suitably substi- tuted carbonyl compounds with styrene subunits leading to benzannulated cyclooctenes. The intramolecular Samarium ketyl addition to arene or hetarene moieties enables a new, efficient, and highly stereoselective entry to dearomatized products such as hexahydronaphthalenes, steroid-like tetra- or pentacyclic compounds, or dihydroindole derivatives. The usefulness of the developed SmI 2 -induced cyclization method was demonstrated by the shortest formal total synthesis of the alkaloid strychnine.
Hansulrich Reissig - One of the best experts on this subject based on the ideXlab platform.
-
towards the core structure of strychnos alkaloids using Samarium diiodide induced reactions of indole derivatives
Chemistry: A European Journal, 2013Co-Authors: Christine Beemelmanns, Steffen Gross, Hansulrich ReissigAbstract:This report describes the development of a first and second generation approach towards the synthesis of the ABCEG pentacyclic core structure of Strychnos alkaloids. First, we discuss a sequential approach applying a series of functional group transformations to prepare suitable precursors for cyclization reactions. These include attempts of Samarium diiodide-induced cyclizations or a Barbier-type reaction of a transient lithium organyl, which successfully led to a tetracyclic key building block earlier used for the synthesis of strychnine. Secondly, we account our first steps towards the development of an atom-economical Samarium diiodide-induced cascade reaction using “dimeric” indolyl ketones as cyclization precursors. In this context, we discuss plausible mechanisms for the Samarium diiodide-induced cascade reaction as well as transformations of the obtained tetracyclic dihydroindoline derivatives.
-
Samarium diiodide induced ketyl het arene cyclisations towards novel n heterocycles
Chemical Society Reviews, 2011Co-Authors: Christine Beemelmanns, Hansulrich ReissigAbstract:In this tutorial review we discuss recent advances in the field of ketyl-(het)arene cyclisations promoted by Samarium diiodide and related processes. Couplings of Samarium ketyls with carbon–carbon multiple bonds are perhaps the most useful reactions to create carbocycles and heterocycles of various ring sizes. They have also successfully been exploited for the synthesis of biologically active compounds or natural products. In this article we intend to summarise our diversity orientated approaches towards nitrogen heterocycles and emphasize other approaches with SmI2 as well as electrochemical cyclisation methods providing similar N-heterocycles. We also briefly discuss our recently published formal total synthesis of strychnine employing a new Samarium diiodide induced cascade reaction as key step. All these examples demonstrate the high synthetic potential of Samarium ketyl-(het)arene cyclisations for the preparation of various types of important heterocyclic compounds.
-
New Samarium diiodide-induced cyclizations
Pure and Applied Chemistry, 2011Co-Authors: Christine Beemelmanns, Hansulrich ReissigAbstract:Samarium diiodide (SmI 2 ) smoothly promotes the cyclizations of suitably substi- tuted carbonyl compounds with styrene subunits leading to benzannulated cyclooctenes. The intramolecular Samarium ketyl addition to arene or hetarene moieties enables a new, efficient, and highly stereoselective entry to dearomatized products such as hexahydronaphthalenes, steroid-like tetra- or pentacyclic compounds, or dihydroindole derivatives. The usefulness of the developed SmI 2 -induced cyclization method was demonstrated by the shortest formal total synthesis of the alkaloid strychnine.
