Development of a Gold-Multifaceted Catalysis Approach to the Synthesis of Highly Substituted Pyrroles: Mechanistic Insights via Huisgen Cycloaddition Studies
作者:Simbarashe Ngwerume、William Lewis、Jason E. Camp
DOI:10.1021/jo302349k
日期:2013.2.1
application of the Huisgen cycloaddition click reaction, which was used to probe the relative stability of substituted O-vinyloximes. The intermediacy of N-alkenylhydroxylamine O-vinyl ethers and imino ketones or imino aldehydes along the reaction pathway were determined by high-temperature 1H, 2H1H}, and 13C1H} NMR experiments. X-ray crystallographic evidence was used to further support the mechanistic hypothesis
通过独立地优化工艺的两个关键步骤,开发了一种直接从肟和炔烃区域选择性合成高度取代的吡咯的金催化新方法。重要的是,阳离子金(I)物种显示出沿反应路径激活多个步骤,因此可作为多面催化剂。最初由金促进的肟氧向活化的炔烃的添加原位提供了O-乙烯基肟。该Ø随后通过金催化的互变异构,[3,3]-σ重排和环脱水过程将-乙烯基肟转化为吡咯。值得注意的是,该方法提供了酯在3/4位的形式的官能团手柄,以便进一步开发。拟议的机理途径得到了Huisgen环加成点击反应的新应用的支持,该反应被用于探测取代的O-乙烯基肟的相对稳定性。的中间性Ñ -alkenylhydroxylamine ø -乙烯基醚和沿反应途径亚氨基酮或亚氨基醛是由高温测定1 H,2 H ^ 1个H},和13 C 11 H NMR实验。X射线晶体学证据被用来进一步支持机理假说。
Rh(III)-Catalyzed Regioselective Synthesis of Pyridines from Alkenes and α,β-Unsaturated Oxime Esters
作者:Jamie M. Neely、Tomislav Rovis
DOI:10.1021/ja3104389
日期:2013.1.9
O-pivaloyl oximes are coupled to alkenes by Rh(III) catalysis to afford substituted pyridines. The reaction with activated alkenes is exceptionally regioselective and high-yielding. Mechanistic studies suggest that heterocycle formation proceeds via reversible C-H activation, alkene insertion, and a C-N bondformation/N-O bond cleavage process.
Intermolecular Cope-Type Hydroamination of Alkenes and Alkynes
作者:André M. Beauchemin、Joseph Moran、Marie-Eve Lebrun、Catherine Séguin、Elena Dimitrijevic、Lili Zhang、Serge I. Gorelsky
DOI:10.1002/anie.200703495
日期:2008.2.8
Access to Cycloalkeno[<i>c</i>]-Fused Pyridines via Pd-Catalyzed C(sp<sup>2</sup>)–H Activation and Cyclization of <i>N</i>-Acetyl Hydrazones of Acylcycloalkenes with Vinyl Azides
A novel Pd(II)-catalyzed vinylic C-H activation and cyclization has been developed, reacting a series of small, medium, and large N-acetyl hydrazones of acylcycloalkenes with vinyl azides to access diverse cycloalkeno[c]-fused pyridine scaffolds. This protocol provides progress in C(sp2)-H bond activation of medium to large cycloalkenes, and the target products can be obtained in a specific regioselectivity with good functional group tolerance and a broad substrate scope.
150. The effect of molecular environment on the absorption spectra of organic compounds in solution. Part III. Compounds containing the chromophore >CC—CN—