Strategies for the Generation of Molecularly Imprinted Polymeric Nitroxide Catalysts
摘要:
[GRAPHICS]Two strategies for preparing catalytically active molecularly imprinted nitroxide-containing polymers are outlined. Both strategies rely upon the thermal rearrangement chemistry of tertiary amine N-oxides. To this end, several polymers were prepared and the polymeric nitroxides were revealed by oxidation with m-CPBA. All of the resulting polymeric catalysts proved to be competent mediators of the oxidation of alcohols.
Strategies for the Generation of Molecularly Imprinted Polymeric Nitroxide Catalysts
摘要:
[GRAPHICS]Two strategies for preparing catalytically active molecularly imprinted nitroxide-containing polymers are outlined. Both strategies rely upon the thermal rearrangement chemistry of tertiary amine N-oxides. To this end, several polymers were prepared and the polymeric nitroxides were revealed by oxidation with m-CPBA. All of the resulting polymeric catalysts proved to be competent mediators of the oxidation of alcohols.
discussed. A correlation by which the rate constant for the C-O bond cleavage of TEMPO-derived alkoxyamines can be predicted from the C-H BDEs of the corresponding alkanes is presented. Solvent effects as well as the effect of camphorsulfonic acid on the rate of the C-O bond homolysis are discussed. Finally, EPR and kinetic evidence show that alkoxyamines derived from nitroxides which are capable of intramolecular
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
Chemical Surface Modification via Radical C−C Bond-Forming Reactions
作者:Kai Oliver Siegenthaler、Andreas Schäfer、Armido Studer
DOI:10.1021/ja0686716
日期:2007.5.1
Radical C−C bond-forming reactions at self-assembled monolayers (SAMs) can be used for the modification of alkene terminated Si wafers under neutral conditions. Many functional groups are tolerated under radical conditions and biologically interesting molecules such as biotin can be immobilized via this approach.
自组装单层 (SAM) 上的自由基 C-C 键形成反应可用于在中性条件下改性烯烃封端的 Si 晶片。许多官能团在自由基条件下是可以耐受的,并且可以通过这种方法固定生物素等生物学感兴趣的分子。
Oxidation of Alkylcatecholboranes with Functionalized Nitroxides for Chemical Modification of Cyclohexene, Perallylated Polyglycerol and of Poly(butadiene)
作者:Christine B. Wagner、Armido Studer
DOI:10.1002/ejoc.201001043
日期:2010.10
and subsequent oxidation by using nitroxides. Oxidation occurs via a radical process and the intermediately formed C-radicals are trapped by the nitroxides to form the corresponding alkoxyamines. If functionalizednitroxides are used, the method allows incorporation of interesting functional moieties via this approach. The novel method is applied for chemicalmodification of cyclohexene as a test substrate
non-acidic aliphatic and benzylicC(sp3)–H bonds was achieved with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in a single-step by employing an aryl ketone as a sole catalyst. The transformation was initiated by homolysis of a C(sp3)–Hbond in starting substance by the photo-excited aryl ketone. The derived carbon radical was then promptly trapped by TEMPO leading to the formation of the TEMPO-adduct.
通过使用芳基,用 2,2,6,6-四甲基哌啶-1-氧基 (TEMPO) 一步实现了非酸性脂肪族和苄基 C(sp3)-H 键的光驱动自由基氧基官能化酮作为唯一的催化剂。该转化是通过光激发芳基酮对起始物质中的 C(sp3)-H 键进行均裂而引发的。然后衍生的碳自由基立即被 TEMPO 捕获,导致 TEMPO 加合物的形成。衍生的 TEMPO 加合物作为醇等价物在合成上是通用的,因为它可以很容易地通过氧化转化为相应的酮,并通过还原转化为相应的醇。实现本催化反应的关键依赖于TEMPO独特的三重作用,它充当氧官能团的前体、再生芳基酮的氧化剂以及防止过度氧化的衍生TEMPO加合物的保护基团。