Impregnated palladium on magnetite as a water compatible catalyst for the cycloisomerization of alkynoic acid derivatives
作者:Beatriz Saavedra、Juana M. Pérez、María J. Rodríguez-Álvarez、Joaquín García-Álvarez、Diego J. Ramón
DOI:10.1039/c8gc00229k
日期:——
This work describes the catalytic activity of palladium(II) species in the cycloisomerization of alkynoicacids and their derivatives in aqueous media as well as in Deep Eutectic Solvents (DESs), with one of the lowest metal catalyst loadings reported so far in the literature. Different substrates such as terminal and internal alkynes or alkynyl sulfonylimides were studied, obtaining selectivity either
Au<sub>2</sub>O<sub>3</sub> as a Stable and Efficient Catalyst for the Selective Cycloisomerization of γ-Acetylenic Carboxylic Acids to γ-Alkylidene-γ-Butyrolactones
The high potential of commercially available Au2O3 as a catalyst in the cyclization of alkynes bearing carboxylic acids to the corresponding γ-alkylidene-γ-butyrolactones through a general, efficient and easy procedure is presented. The reaction shows a high degree of chemo-, regio-, and stereoselectivity. The 5-exo mode of cyclization and anti auration are a general trend for the Au2O3 catalyst.
Synthesis of Enol Lactones via Cu(I)-Catalyzed Intramolecular O-Vinylation of Carboxylic Acids
作者:Changhui Sun、Yewen Fang、Shuang Li、Yue Zhang、Qiwu Zhao、Shana Zhu、Chaozhong Li
DOI:10.1021/ol9015578
日期:2009.9.17
catalysis of CuI/trans-N,N′-dimethylcyclohexane-1,2-diamine, a number of carboxylic acids underwent efficient intramolecular O-vinylation with vinyl bromides leading to the synthesis of the corresponding five- and six-membered enollactones. The same catalytic system also led to the efficient cycloisomerization of alkynoic acids.
Transition-metal catalyzed synthesis of δ-hydroxy-γ-lactones from bis(trimethylsilyl) ketene acetals and allylic acetates via γ-unsaturated carboxylic acids. Comments on the formation of α-cyclopropyl carboxylic acids
Bis(trimethylsilyl)keteneacetals react with allylic acetates in the presence of Pd(0) complexes to give γ-unsaturated carboxylic acids together with α-cyclopropyl carboxylic acids. The unsaturated acids can be converted catalytically to δ-hydroxy-γ-lactones by the H2O2/MTO system (methyltrioxorhenium) and to butenolides by Pd(II) catalyzed intramolecular cyclization reactions. The structure of two
双(三甲基甲硅烷基)乙烯酮缩醛在Pd(0)配合物的存在下与乙酸烯丙酯反应生成γ-不饱和羧酸与α-环丙基羧酸。H 2 O 2 / MTO系统(甲基三氧or)可将不饱和酸催化转化为δ-羟基-γ-内酯,而Pd(II)催化的分子内环化反应则可将其转化为丁烯化物。这些内酯中的两个的结构已经通过X射线分析确定。将讨论环丙酸的形成机理。
Iridium-Catalyzed Intramolecular Oxidative Cyclization of Alkenyl Amides and Alkenoic Acids
Published as part of the Special Topic Modern Cyclization Strategies in Synthesis Abstract An iridium/dppf complex efficiently catalyzed the oxidativecyclization of N-sulfonyl alkenyl amides and alkenoic acids. Electron-deficient alkenes were effective as sacrificial hydrogen acceptors. High selectivity of the oxidativecyclization over the competing addition reaction has been realized by the use