将单线态氧(1 O 2)添加到辅助束缚的1,4-二烯的近端烯烃中以及将三线态氧(3 O 2)添加到相应的戊二烯基的近端位置中均产生适度的共轭二烯氢过氧化物到高的非对映异构体过量。由于缺乏对烯烃构象的控制,对于向Z,Z-庚二烯的远端烯烃加成1 O 2,观察到可忽略的立体选择。尽管有证据表明戊二烯基是高度受约束的中间体,但远端添加3 O 2的非对映选择性也很差。。自由基氧合期间观察到的烯烃异构化程度可能与中间戊二烯基和过氧自由基的空间限制相关,并且可能与非天然脂肪酸酶促氧合期间烯烃异构化的文献报道有关。
Enantioselective Photoredox Catalysis Enabled by Proton-Coupled Electron Transfer: Development of an Asymmetric Aza-Pinacol Cyclization
作者:Lydia J. Rono、Hatice G. Yayla、David Y. Wang、Michael F. Armstrong、Robert R. Knowles
DOI:10.1021/ja4100595
日期:2013.11.27
protocol for the reductive coupling of ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by a chiral phosphoric acid catalyst and the photoredox catalyst Ir(ppy)2(dtbpy)PF6. Remarkably, these neutral ketyl radicals appear to remain H-bonded to the chiral conjugate
报道了第一个用于酮和腙还原偶联的高度对映选择性催化方案。这些反应通过由手性磷酸催化剂和光氧化还原催化剂 Ir(ppy)2(dtbpy)PF6 共同介导的协同质子耦合电子转移 (PCET) 事件产生的中性羰基自由基中间体进行。值得注意的是,在随后的 CC 键形成步骤过程中,这些中性羰基自由基似乎保持与布朗斯台德酸的手性共轭碱 H 键合,从而提供具有优异水平的非对映选择性和对映选择性的顺式 1,2-氨基醇衍生物. 这项工作首次证明了不对称催化中协同 PCET 活化的可行性和潜在益处。
Nickel-catalyzed cross-couplings of cyclohexenyl phosphate and arylboronic acids
作者:Yang Nan、Zhen Yang
DOI:10.1016/s0040-4039(99)00517-1
日期:1999.4
The Nickel-catalyzedcross-coupling reaction of cyclohexenylphosphate with a variety of arylboronicacids is described here for the first time. This methodology opens the door to other palladium or nickel-catalyzed coupling reactions involving vinyl phosphates.
Selective arylation at the vinylic site of cyclic olefins
作者:Xiaojin Wu、Jianrong (Steve) Zhou
DOI:10.1039/c3cc41722k
日期:——
Cyclicolefins usually give Heck products having an aryl ring residing at the allylic or homoallylic position. We describe herein a new method that allows arylation at the vinylic position of various cyclicolefins.
Cross-coupling of Aryl/Alkenyl Silyl Ethers with Grignard Reagents through Nickel-catalyzed C–O Bond Activation
作者:Fei Zhao、Da-Gang Yu、Ru-Yi Zhu、Zhenfeng Xi、Zhang-Jie Shi
DOI:10.1246/cl.2011.1001
日期:2011.9.5
C–O activation and its application have drawn much attention since oxygen-based electrophiles are easily available, less toxic, and more environmentally benign. This letter presents systematically results on the Ni-catalyzed Kumada–Tamao–Corriu coupling based on siloxy arenes/alkenes, which provides a new strategy of silyl protection/C–C bond formation sequence in organic synthesis.
A Convenient Synthesis of 2-Naphthylcyclopentanones and 2-Naphthylcyclohexanones from 1-Naphthylcycloalkenes
作者:Maciej Góra、Michał K. Łuczyński、Janusz J. Sepioł
DOI:10.1055/s-2005-865298
日期:——
The oxidation of naphthylcycloalkenes with hydrogen peroxide or MCPBA followed by acid catalyzed rearrangement of diol (epoxide), afforded a series of naphthylcycloalkanones in a very simple manner. The conditions allow preparation of naphthylcycloalkanones on a multigram scale.