作者:Paul J. Kropp、Norbert J. Pienta、Joy A. Sawyer、Richard P. Polniaszek
DOI:10.1016/s0040-4020(01)92370-1
日期:——
The previously observed cyclopropaoation of alkenes by irradiation of diiodomethane (I) in their presence has been studied in more detail and found to be a synthetically useful procedure which is significantly less subject to steric effects than the traditional Simmons-Smith method. The results from photocyclopropanation of a variety of alkenes are summarized in Tables 1 and 3–4. In a number of cases
Manganese(II)/Picolinic Acid Catalyst System for Epoxidation of Olefins
作者:Ross A. Moretti、J. Du Bois、T. Daniel P. Stack
DOI:10.1021/acs.orglett.6b00518
日期:2016.6.3
An in situ generated catalyst system based on Mn(CF3SO3)2, picolinic acid, and peracetic acid converts an extensive scope of olefins to their epoxides at 0 °C in <5 min, with remarkable oxidant efficiency and no evidence of radical behavior. Competition experiments indicate an electrophilic active oxidant, proposed to be a high-valent Mn = O species. Ligand exploration suggests a general ligand sphere
基于Mn(CF 3 SO 3)2,吡啶甲酸和过氧乙酸的原位生成的催化剂体系在0°C下于<5分钟内将大量烯烃转化为环氧化物,具有显着的氧化效率并且没有自由基的迹象行为。竞争实验表明,一种亲电子活性氧化剂被认为是高价Mn = O物种。配体探索表明,一般的配体球基序有助于有效氧化。该方法以其简单性和使用廉价试剂来快速获得高附加值产品而得到强调。
Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydrofunctionalization and Formal Retro-hydrofunctionalization
作者:Steven Hanna、Trevor W. Butcher、John F. Hartwig
DOI:10.1021/acs.orglett.9b02695
日期:2019.9.6
We report a contra-thermodynamic isomerization of internal olefins to terminal olefins driven by redox reactions and formation of Si-F bonds. This process involves chain-walking hydrosilylation of internal olefins and subsequent formal retro-hydrosilylation. The process rests upon the high activities of platinum hydrosilylation catalysts for isomerization of metal alkyl intermediates and a new, metal-free
Dendrimer‐Encapsulated Pd Nanoparticles, Immobilized in Silica Pores, as Catalysts for Selective Hydrogenation of Unsaturated Compounds
作者:Edward A. Karakanov、Anna V. Zolotukhina、Andrey O. Ivanov、Anton L. Maximov
DOI:10.1002/open.201800280
日期:2019.3
on the presence of Si(OEt)4, while dendrimer molecules acting as both anchored ligands and template, demonstrated the maximum activity in the hydrogenation of terminal linear alkynes and conjugated dienes, reaching TOF values up to 400000 h−1. Herein the total selectivity on alkene in the case of terminal alkynes and conjugated dienes reached 95–99 % even at hydrogen pressure of 30 atm. The catalysts
通过原位共水解获得的基于固定在二氧化硅孔和网络中的聚(丙烯亚胺)树枝状聚合物的多相含钯纳米催化剂已被合成并在各种不饱和化合物的氢化中进行了检验。发现催化剂活性和选择性强烈依赖于载体结构以及底物电子和几何特征。因此,在聚合物模板和四乙氧基硅烷存在下合成的介孔催化剂显示出在各种苯乙烯(包括大体积和刚性的二苯乙烯及其异构体)的氢化中具有最大活性,达到约230000 h -1的TOF值。在聚合物模板存在下合成的其他介孔催化剂,但不添加 Si(OEt) 4,提供了反式环辛烯形成的选择性为 90-95%,与基于均相树枝状聚合物的催化剂相似。仅在 Si(OEt) 4存在下获得的微孔催化剂,同时充当锚定配体和模板的树枝状聚合物分子,在末端直链炔烃和共轭二烯的氢化中表现出最大活性,TOF 值高达 400000 h -1。在此,即使在 30 atm 的氢气压力下,对于末端炔烃和共轭二烯,烯烃的总选择性也达到
Mesoporous organic Pd-containing catalysts for the selective hydrogenation of conjugated hydrocarbons
作者:E. A. Karakhanov、A. L. Maksimov、I. A. Aksenov、V. S. Kuznetsov、T. Yu. Filippova、S. V. Kardashev、D. S. Volkov
DOI:10.1007/s11172-014-0657-9
日期:2014.8
Palladium catalysts supported on ordered organic mesoporous polymers were synthesized. The catalysts are characterized by the narrow size distribution of palladium nanoparticles with an average particle size of 2.2–5.2 nm. They demonstrate high catalytic activity and selectivity in phenylacetylene hydrogenation (896–2590 min−1, selectivity 89–98%). High activity and selectivity for alkenes are observed in the hydrogenation of conjugated dienes (for isoprene, TOF = 1850–5000 min−1, selectivity 99%; for 2,5-dimethyl-2,4-hexadiene, TOF = = 1294–2400 min−1, selectivity 100%; for 1,4-diphenyl-1,3-butadiene, TOF = 14–22 min−1, selectivity 7–16%). A dependence of the selectivity on the nature of the support and substrate was found for the hydrogenation of 1,4-diphenyl-1,3-butadiene.