Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst
作者:Bin Zhao、Bo Xu
DOI:10.1039/d0ob02417a
日期:——
coumarin derivatives via a tandem double bond isomerization/oxidative cyclization of cinnamic acids. Inexpensive and stable xanthone was used as the photocatalyst, and readily available Selectfluor was used as the oxidant. This method tolerates a wide range of functional groups and offers excellent chemical yields in general. Besides, the photocatalytic oxidative cyclization of cinnamic acid esters gives
One Photocatalyst, <i>n</i> Activation Modes Strategy for Cascade Catalysis: Emulating Coumarin Biosynthesis with (−)-Riboflavin
作者:Jan B. Metternich、Ryan Gilmour
DOI:10.1021/jacs.5b12081
日期:2016.1.27
energy transfer (ET) and single-electron transfer (SET) activation pathways, respectively. This catalytic approach has been utilized to emulate the coumarin biosynthesis pathway, which features a key photochemical E → Z isomerization step. Since the ensuing SET-based cyclization eliminates the need for a prefunctionalized aryl ring, this constitutes a novel disconnection of a pharmaceutically important
使用单一催化剂产生分子复杂性,其中必要的活化模式随着反应的进行而依次利用,是合成中一个有吸引力的指导原则。这要求每个底物转位都暴露出一种催化剂活化模式 (AM),所有先前或未来的中间体都对这种模式具有抵抗力。虽然麦克米伦将烯胺和亚胺离子活化的美丽结合体现了这一概念,但当代催化其他领域的例子仍然难以捉摸。在这里,我们将此策略扩展到有机光化学。通过利用 (-)-核黄素的两种离散光化学活化模式,可以分别通过能量转移 (ET) 和单电子转移 (SET) 激活途径依次诱导异构化和环化。这种催化方法已被用于模拟香豆素生物合成途径,该途径具有关键的光化学 E → Z 异构化步骤。由于随后的基于 SET 的环化消除了对预官能化芳环的需要,这构成了药学重要支架的新断开连接。
friendly, and highly efficient, metal-free, visiblelight mediated organophotocatalysed method has been devised for synthesizing potentially biologically active substituted coumarin scaffolds. This method involves the reaction between substituted ethynylbenzene and substituted phenyl formate undervisiblelight photoredox catalysedconditions at room temperature using acridinium as photocatalyst. The distinctive
Coumarins by Direct Annulation: β‐Borylacrylates as Ambiphilic C
<sub>3</sub>
‐Synthons
作者:Max Wienhold、John J. Molloy、Constantin G. Daniliuc、Ryan Gilmour
DOI:10.1002/anie.202012099
日期:2021.1.11
2‐halo‐phenol derivatives to generate structurally and electronically diverse coumarins. Key to this [3+3] disconnection is the BPin unit which serves a dual purpose as both a traceless linker for C(sp2)–C(sp2) coupling, and as a chromophore extension to enable inversion of the alkene geometry via selective energy transfer catalysis. Mild isomerisation is a pre‐condition to access 3‐substituted coumarins
Metal-free C(3)–H arylation of coumarins promoted by catalytic amounts of 5,10,15,20-tetrakis(4-diethylaminophenyl)porphyrin
作者:Masahiro Kojima、Kounosuke Oisaki、Motomu Kanai
DOI:10.1039/c5cc02349a
日期:——
Metal-free, Meerwein-type C(3)–H arylation of coumarins was achieved in the presence of catalytic amounts of 5,10,15,20-tetrakis(4-diethylaminophenyl)porphyrin.