Synthesis and Reduction Kinetics of Sterically Shielded Pyrrolidine Nitroxides
摘要:
A series of sterically shielded pyrrolidine nitroxides were synthesized, and their reduction by ascorbate (vitamin C) indicate that nitroxide 3, a tetraethyl derivative of 3-carboxy-PROXYL, is reduced at the slowest rate among known nitroxides, i.e., at a 60-fold slower rate than that for 3-carboxy-PROXYL.
Radical Carboaminoxylation with Subsequent Pd-Catalyzed Intramolecular Allylation for the Construction of Five- and Six-Membered Carbocycles
作者:Armido Studer、Birte Schulte
DOI:10.1055/s-2006-942416
日期:2006.7
Regioselective intermolecular radical carboaminoxylation using various alkoxyamines are presented. These environmentally benign tin-free radical additions can either be performed under microwave conditions at 180 °C or by using conventional heating at 125 °C. Intermolecular Trost-Tsuji allylation of the carboaminoxylation products provide five- and six-membered carbocycles in moderate to good yields. The radical addition/Pd-catalyzed intramolecular allylation can be performed as one-pot process.
1,3-Dithiane-Derived Alkoxyamines as One-Carbon Radical Precursors
作者:Armido Studer、Antonio J. Herrera
DOI:10.1055/s-2005-865288
日期:——
A new method for the generation of C-2 centered radicals derived from 1,3-dithiane is presented. The radical precursors, 2-dialkylaminoxyl-l,3-dithianes, are readily prepared from 1,3-dithiane and stablenitroxides. Thermal reaction of 2-dialkylaminoxyl-1,3-dithianes with electron-deficient olefins affords carboaminoxylation products or oxidative addition products depending on the nitroxide used. The
Two organic radical contrast agents, TEMPO-Glc and TEEPO-Glc, were synthesized and their stabilities and contrast enhancing properties were tested with in vitro NMR and MRI experiments.
Tin-Free Radical Alkoxyamine Addition and Isomerization Reactions by Using the Persistent Radical Effect: Variation of the Alkoxyamine Structure
作者:Kian Molawi、Tobias Schulte、Kai Oliver Siegenthaler、Christian Wetter、Armido Studer
DOI:10.1002/chem.200400936
日期:2005.4.8
Various C-centered radicals can efficiently be generated through thermal C-O-bond homolysis of alkoxyamines. This method is used to perform environmentally benign radical cyclization and intermolecular addition reactions. These alkoxyamine isomerizations and intermolecular carboaminoxylations are mediated by the persistent radicaleffect (PRE). In the paper, the effect of the variation of the alkoxyamine
Steric and Electronic Effects in Cyclic Alkoxyamines—Synthesis and Applications as Regulators for Controlled/Living Radical Polymerization
作者:Christian Wetter、Johannes Gierlich、Christoph Alexander Knoop、Christoph Müller、Tobias Schulte、Armido Studer
DOI:10.1002/chem.200305427
日期:2004.3.5
trimethylsilyl(TMS)-diazomethane. The use of the new alkoxyamines as regulators/initiators for radical polymerization is discussed. Efficient controlled and livingpolymerization of styrene and n-butyl acrylate was obtained with the six-membered tetraethyl alkoxyamine 13. Controlledpolymerizations can be conducted even at 90 degrees C. In addition, alkoxyamine 13 can be used for the preparation of AB diblock