Stereoselective Synthesis of Fluoroalkenoates and Fluorinated Isoxazolidinones: N-Substituents Governing the Dual Reactivity of Nitrones
作者:G. K. Surya Prakash、Zhe Zhang、Fang Wang、Martin Rahm、Chuanfa Ni、Marc Iuliucci、Ralf Haiges、George A. Olah
DOI:10.1002/chem.201303509
日期:2014.1.13
α‐Fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones are of vast interest due to their potential biological applications. We now demonstrate the syntheses of (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones by the reactions between nitrones and α‐fluoro‐α‐bromoacetate. By altering N‐substituents in nitrones, (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones can be achieved, respectively, with
Evidence for the Intermediacy of Arylbenzylnitrenium Ions in the Thermal Rearrangement of Isoxazolidines Derived from C,N-Diarylnitrones and 2-Morpholin-4-yl-acrylonitrile
arylbenzylnitrenium ions. Herein, we report that these species can be generated by a process involving an unprecedented thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile. The products from these reactions are dramatically dependent upon the nature of the nitrone. Most of the observed chemistry originates from the singlet state.
Iron and Ruthenium Lewis Acid Catalyzed Asymmetric 1,3-Dipolar Cycloaddition Reactions between Nitrones and Enals
作者:Florian Viton、Gérald Bernardinelli、E. Peter Kündig
DOI:10.1021/ja017814f
日期:2002.5.1
The single coordination-site transition metal Lewisacids [CpM(BIPHOP-F)][SbF6] (M = Fe, Ru) catalyze the [3+2] dipolar cycloadditionreaction between reactive nitrones and alpha,beta-unsaturated aldehydes to give chiral isoxazolidines with ee values of 75 to >96%. The stereochemistry of the major enantiomer is consistent with an endo approach of the nitrone to the Calpha-Si-face of the enal in the s-trans
Efficient Synthesis of Isoxazolidine-Tethered Monolayer-Protected Gold Nanoparticles (MPGNs) via 1,3-Dipolar Cycloadditions under High-Pressure Conditions
作者:Jun Zhu、Brandon M. Lines、Michael D. Ganton、Michael A. Kerr、Mark S. Workentin
DOI:10.1021/jo702398r
日期:2008.2.1
3-dipolar cycloaddition. At atmospheric pressures, the reaction proceeds slowly (if at all) and makes this reaction impractical for the synthetic modification of the nanoparticles. However, by performing the reaction under the high-pressure conditions, the reaction proceeds efficiently and quantitatively. TEM shows that the use of high pressure does not affect the size of the goldnanoparticle core. The
制备了包含约30%马来酰亚胺封端的十二烷硫醇盐/十二烷硫醇盐配体的马来酰亚胺改性的2.5±0.5nm混合单层保护的金纳米颗粒(2- C 12 MPGN)。的2 -C 12 MPGN用一系列硝酮(的反应一-我)在常压和高压(11 000个大气压)的条件下,形成相应的异恶唑烷改性的纳米粒子(3 -C 12MPGN)通过界面上的1,3-偶极环加成反应。在大气压下,反应进行得很慢(如果有的话),使该反应对于纳米粒子的合成改性不切实际。然而,通过在高压条件下进行反应,反应有效且定量地进行。TEM显示高压的使用不影响金纳米颗粒核的尺寸。通过1 H NMR光谱对3 -C 12 MPGN进行表征,方法是将与使用N-十二烷基马来酰亚胺(4)和相同的硝酮(a - i)形成5的模型反应得到的光谱进行比较。。另外,与具有所有硝酮的2- C 12 MPGN相比,用4进行环加成反应也更容易发生,这表明后者的环境会影响环加成反应。
Reaction of nitrones with trimethylsilylketene
作者:Kiyo Takaoka、Toyohiko Aoyama、Takayuki Shioiri
DOI:10.1016/s0040-4039(99)00407-4
日期:1999.4
Trimethylsilylketene smoothly reacts with α,N-diarylnitrones to give oxindoles in good yields. On the other hand, the reaction of trimethylsilylketene with N-arylmethylnitrones gives a mixture of N,N-diacylamines and N-acylamines.