在室温下可见光照射下,核黄素四乙酸酯有效地催化了脂肪族羧酸与芳基苯乙烯基砜的脱羧烯基化反应。这种无金属方案具有成本效益、环境友好,并为相应的烯烃提供出色的 ( E )-非对映控制。该方法还可用于通过使用炔基砜作为自由基受体来区域选择性地制备内部炔烃。通过进行 ( E ) 到 ( Z ) 光异构化、铁催化的由 2-苯氧基羧酸底物衍生的苯氧基的烯丙基取代,以及合成-环氧化和非对映选择性分子内碘芳基化。基于对照实验和 DFT 计算,我们提出了一种反应机制,可以解释观察到的区域选择性和非对映选择性。
Visible-Light-Mediated C–I Difluoroallylation with an α-Aminoalkyl Radical as a Mediator
作者:Fuyang Yue、Jianyang Dong、Yuxiu Liu、Qingmin Wang
DOI:10.1021/acs.orglett.1c02905
日期:2021.9.17
for direct visible-light-mediated C–I difluoroallylation reactions of α-trifluoromethyl arylalkenes with alkyliodides at room temperature with an α-aminoalkyl radical as a mediator. The protocol permits efficient functionalization of various α-trifluoromethyl arylalkenes with cyclic and acyclic primary, secondary, and tertiary alkyliodides and is scalable to the gram level. This mild protocol uses
Visible-Light-Mediated Alkenylation, Allylation, and Cyanation of Potassium Alkyltrifluoroborates with Organic Photoredox Catalysts
作者:Drew R. Heitz、Komal Rizwan、Gary A. Molander
DOI:10.1021/acs.joc.6b01207
日期:2016.8.19
and ruthenium-free approaches to protectedallylicamines and alkyl nitriles under photoredox conditions are reported. An inexpensive organic dye, eosin Y, catalyzes coupling of Boc-protected potassium α-aminomethyltrifluoroborates with a variety of substituted alkenyl sulfones through an α-aminomethyl radical addition–elimination pathway. Allylic and homoallylic amines were formed in moderate yields
Mechanistic dichotomy in the solvent dependent access to <i>E vs. Z</i>-allylic amines <i>via</i> decarboxylative vinylation of amino acids
作者:Samir Manna、Shunta Kakumachi、Kanak Kanti Das、Youichi Tsuchiya、Chihaya Adachi、Santanu Panda
DOI:10.1039/d2sc02090d
日期:——
donor–acceptor based photocatalysts. The solvent-dependent access to E vs. Z-allylic amines was achieved via decarboxylative vinylation of amino acids with vinyl sulfones. Detailed experimental studies have been conducted to understand the role of the solvent in the reactivity and stereoselectivity of the vinylation reactions.
Alkylboronic acids as alkylating agents: photoredox-catalyzed alkylation reactions assisted by K<sub>3</sub>PO<sub>4</sub>
作者:Fuyang Yue、Henan Ma、Hongjian Song、Yuxiu Liu、Jianyang Dong、Qingmin Wang
DOI:10.1039/d2sc05521j
日期:——
alkylboronic acids in organic synthesis, their utility as alkyl radical precursors in visible-light-induced photocatalytic reactions is limited by their high oxidation potentials. In this study, we demonstrated that an inorganophosphorus compound can modulate the oxidation potentials of alkylboronic acids so that they can act as alkyl radical precursors. We propose a mechanism based on the results of fluorescence
尽管烷基硼酸在有机合成中无处不在,但它们在可见光诱导的光催化反应中作为烷基自由基前体的用途受到其高氧化电位的限制。在这项研究中,我们证明了一种无机磷化合物可以调节烷基硼酸的氧化电位,使其可以作为烷基自由基前体。我们根据荧光猝灭实验、电化学实验、 11 B 和31的结果提出了一种机制P NMR 光谱和其他技术。此外,我们描述了一种简单可靠的烷基化方法,该方法具有良好的官能团耐受性,可用于直接 C-B 氯化、氰化、乙烯基化、炔基化和烯丙基化,以及衍生药物分子的后期功能化。值得注意的是,烷基硼酸可以在硼频哪醇酯的存在下被选择性地激活。
Regioselective Alkynylation and Alkenylation at the More Hindered C–B Bond of 1,2-Bis(Boronic) Esters
effective synthetic methods stands in stark contrast to the large number of encumbered sites encountered in molecules of interest. Here, we demonstrate that 1,2-bis(boronates) undergo selective alkynylation and alkenylation at the more sterically hindered C–B bond. Our preliminary mechanistic studies disclosed that this reaction can proceed through two convergent pathways involving direct coupling of sterically