Titania-Promoted Carboxylic Acid Alkylations of Alkenes and Cascade Addition–Cyclizations
作者:David W. Manley、Roy T. McBurney、Phillip Miller、John C. Walton、Andrew Mills、Christopher O’Rourke
DOI:10.1021/jo4027929
日期:2014.2.7
electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredoxcatalyst under different
使用 TiO 2 的光化学反应和羧酸在干燥厌氧条件下导致几种类型的 C-C 键形成过程与缺电子烯烃。烷基化的效率随羧酸中的取代基而显着变化。芳氧基乙酸与马来酰亚胺的反应导致了一个级联过程,其中吡咯并色烯衍生物伴随着烷基化的琥珀酰亚胺。通过在不同条件下使用光氧化还原催化剂,可以在一定程度上调整这些产品中的一种或其他产品的选择性。通过包含 2-烯基、2-芳基或 2-肟基官能团而适用于分子内闭环的芳氧基乙酸反应相当差。这些系统的反应物消耗和产物形成的概况是通过原位核磁共振监测技术获得的。对一系列不同的催化剂形式进行了效率和易用性测试。所提出的机制,涉及在 TiO2 上的空穴捕获2表面由羧酸盐随后 CO 2损失得到中间体的 EPR 光谱证据的支持。氘标记表明二氧化钛可能从表面羟基提供质子并提供电子和空穴,因此既是催化剂又是反应伙伴。
C(sp
<sup>3</sup>
)–H functionalizations of light hydrocarbons using decatungstate photocatalysis in flow
作者:Gabriele Laudadio、Yuchao Deng、Klaas van der Wal、Davide Ravelli、Manuel Nuño、Maurizio Fagnoni、Duncan Guthrie、Yuhan Sun、Timothy Noël
DOI:10.1126/science.abb4688
日期:2020.7.3
alkyl halide reagents. Laudadio et al. now report a convenient method to add ethane and propane directly across conjugated olefins with no prefunctionalization or byproducts (see the Perspective by Oksdath-Mansilla). The C–H bond scission in this hydroalkylation is accomplished by a decatungstate photocatalyst that also acts as a hydrogen atom transfer agent to complete the process. The reaction, optimized
C(sp<sup>3</sup>)–C(sp<sup>3</sup>) coupling of non-activated alkyl-iodides with electron-deficient alkenes <i>via</i> visible-light/silane-mediated alkyl-radical formation
作者:Sanesh Mistry、Roopender Kumar、Andrew Lister、Matthew J. Gaunt
DOI:10.1039/d2sc03516b
日期:——
Here, we present a remarkably mild and general initiation protocol for alkyl-radical generation from non-activated alkyl-iodides. An interaction between a silane and an alkyl iodide is excited by irradiation with visible light to trigger carbon–iodide bond homolysis and form the alkyl radical. We show how this method can be developed into an operationally simple and general Giese addition reaction