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On the Hydrostannylation of Aryl Propargylic Alcohols and Their Derivatives: Remarkable Differences in Both Regio‐ and Stereoselectivity in Radical‐ and Nonradical‐Mediated Transformations 下载免费PDF全文
Dr. Martins S. Oderinde Dr. Robert D. J. Froese Prof. Michael G. Organ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8579-8583
Herein, we describe a highly regio‐ and stereoselective radical‐mediated and molecular‐oxygen (O2)‐dependent hydrostannylation of phenyl propargylic alcohols and their derivatives. There is a significant steric effect on the stereoselectivity of the tin‐radical addition. Further, the uncatalyzed regio‐ and stereoselective hydrostannylation of aryl propargylic alcohols with nBu3SnH and Ph3SnH is also described and occurs with near titration kinetics. Although the uncatalyzed addition with nBu3SnH gave a remarkable γ‐regioselectivity irrespective of the electronic nature of the aryl moiety, addition with Ph3SnH appears to be driven by the electronic nature of the aryl alkynes. 相似文献
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Ronald Grigg William S. MacLachlan David T. MacPherson Visuvanathar Sridharan Selvaratnam Suganthan 《Tetrahedron》2001,57(52):10335-10345
Up to four bonds and five stereocentres are created, in five component processes (five point diversity), utilising resin bound aryl iodides by hydroboration or hydrostannylation of alkynes, followed by cyclisation–anion capture involving Suzuki or Stille reactions. Three small libraries were prepared to validate the chemistry. 相似文献
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Reaction Mechanism of the Hydrogermylation/Hydrostannylation of Unactivated Alkenes with Two‐Coordinate EII Hydrides (E=Ge,Sn): A Theoretical Study 下载免费PDF全文
Dr. Lili Zhao Dr. Markus Hermann Prof. Dr. Cameron Jones Prof. Dr. Gernot Frenking 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11728-11735
Quantum chemical calculations using density functional theory with the TPSS+D3(BJ) and M06‐2X+D3(ABC) functionals have been carried out to understand the mechanisms of catalyst‐free hydrogermylation/hydrostannylation reactions between the two‐coordinate hydrido‐tetrylenes :E(H)(L+) (E=Ge or Sn, L+=N(Ar+)(SiiPr3); Ar+=C6H2{C(H)Ph2}2iPr‐2,6,4) and a range of unactivated terminal (C2H3R, R=H, Ph, or tBu) and cyclic [(CH)2(CH2)2(CH2)n, n=1, 2, or 4] alkenes. The calculations suggest that the addition reactions of the germylenes and stannylenes to the cyclic and acyclic alkenes occur as one‐step processes through formal [2+2] addition of the E?H fragment across the C?C π bond. The reactions have moderate barriers and are weakly exergonic. The steric bulk of the tetrylene amido groups has little influence on the activation barriers and on the reaction energies of the anti‐Markovnikov pathway, but the Markovnikov addition is clearly disfavored by the size of the substituents. The addition of the tetrylenes to the cyclic alkenes is less exergonic than the addition to the terminal alkenes, which agrees with the experimentally observed reversibility of the former reactions. The hydrogermylation reactions have lower activation energies and are more exergonic than the stannylene addition. An energy decomposition analysis of the transition state for the hydrogermylation of cyclohexene shows that the reaction takes place with simultaneous formation of the Ge?C and (Ge)H?C′ bonds. The dominant orbitals of the germylene are the σ‐type lone pair MO of Ge, which serves as a donor orbital, and the vacant p(π) MO of Ge, which acts as acceptor orbital for the π* and π MOs of the olefin. Inspection of the transition states of some selected reactions suggests that the differences between the activation energies come from a delicate balance between the deformation energies of the interacting species and their interaction energies. 相似文献
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(Z)-α-Arylthio-α,β-unsaturated ketones can be stereoselectively synthesized in one pot under mild conditions, in good yields, by the palladium-catalyzed hydrostannylation of acetylenic sulfides with tributyltin hydride, followed by Stille coupling with acyl chlorides. 相似文献
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炔基砜和三丁基锡化氢在四(三苯基膦)钯催化下于苯中室温下进行锡氢化反应4 h,经溶剂转换成DMF后,再在CuI助催化剂存在下与炔基溴化物于室温进行Stille偶联反应,以良好产率且立体选择性地合成了( Z)-2-砜基取代的1,3-烯炔。该“一锅”合成法具有起始原料易得、反应条件温和、操作简便、钯催化剂利用率高和产率好等优势。 相似文献
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Palladium-catalyzed hydrostannylation of alkynyl esters in benzene at room temperature gives stereoselectively (E)-α-stannyl-α,β-unsaturated esters 1 in good yields. (E)-α-Stannyl-α,β-unsaturated esters 1 are difunctional group reagents that undergo Stille coupling reactions with alkenyl halides 2 in the presence of Pd(PPh3)4 and CuI co-catalyst to afford stereoselectively (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes 3 in good yields. 相似文献