Synthesis of Spirolactones via a BF<sub>3</sub>·Et<sub>2</sub>O-Promoted Cascade Annulation of α-Keto Acids and 1,3-Enynes
作者:Beibei Zhao、Zhen Zhang、Pinhua Li、Tao Miao、Lei Wang
DOI:10.1021/acs.orglett.1c01827
日期:2021.8.6
A novel and effective method for the synthesis of spirolactones from readily available α-keto acids and 1,3-enynes is developed via a BF3·Et2O-promoted cascade annulation. This sequential process is conducted at room temperature, and it provides the functionalized spirolactones in good to excellent yield under metal-free conditions.
Acyl Radicals from α-Keto Acids Using a Carbonyl Photocatalyst: Photoredox-Catalyzed Synthesis of Ketones
作者:Da-Liang Zhu、Qi Wu、David James Young、Hao Wang、Zhi-Gang Ren、Hong-Xi Li
DOI:10.1021/acs.orglett.0c02351
日期:2020.9.4
Acylradicals have been generated from α-keto acids using inexpensive and commercially available 2-chloro-thioxanthen-9-one as the photoredox catalyst under visible light illumination. These reactive species added to olefins or coupled with aryl halides via a bipyridyl-stabilized Ni(II) catalyst, enabling easy access to a diverse range of ketones. This reliable, atom-economical, and eco-friendly protocol
Photoredox Functionalization of 3-Halogenchromones, 3-Formylchromones, and Chromone-3-carboxylic Acids: Routes to 3-Acylchromones
作者:Satenik Mkrtchyan、Viktor O. Iaroshenko
DOI:10.1021/acs.joc.0c00537
日期:2020.6.5
describes a set of new and efficient syntheticroutes toward 3-acyl-substituted chromones ranging from readily available chromone precursors, namely 3-halogenchromones, 3-formylchromones, and chromone-3-carboxylic acids by means of visible-light photoredox catalysis. The operationally simple protocols transform a wide variety of chromone derivatives into challenging 3-acyl-substituted chromones in excellent
photoinduced acylation of N‐heterocycles is explored. This visible‐lighttriggered reaction occurs not only under extremely mild reaction conditions, but also does not require the presence of a photosensitizer. The mechanistic studies suggest formation of EDA complexes prompt to harness the energy from visible‐light. Compatibility with a large panel of α‐keto acids as acyl precursors and an array of N‐heterocycles
Visible-Light-Induced Decarboxylative Cyclization of 2-Alkenylarylisocyanides with α-Oxocarboxylic Acids: Access to 2-Acylindoles
作者:Xiaofei Zhang、Peiyuan Zhu、Ruihong Zhang、Xiang Li、Tuanli Yao
DOI:10.1021/acs.joc.0c00039
日期:2020.8.7
efficient and practical protocol for visible-light-induced decarboxylative cyclization of 2-alkenylarylisocyanides with α-oxocarboxylic acids has been developed, which afforded a broad range of 2-acylindoles in moderate to good yields. The reaction proceeds through a cascade of acyl radical addition/cyclization reactions under irradiation of an Ir3+ photoredox catalyst without external oxidants and