491-38-3Relevant articles and documents
Lewis Acid-catalysed Facile Elimination of the Diazo Group in 3-Diazochromanones. Novel Conversion of Chromanones into Chromones
Mandal, Pranab,Venkateswaran, Ramanathapuram V.
, p. 88 - 89 (1998)
3-Diazochromanones undergo rapid elimination of the diazo group in presence of BF3- Et2O to furnish chromones.
Oxidation of chromanones and 2-spirochromanones with [hydroxy(tosyloxy)iodo]benzene in acetonitrile under reflux as well as ultrasound: A convenient route for the synthesis of chromones, tetrahydroxanthones and their higher homologues
Kumar,Singh,Prakash,Singh
, p. 2637 - 2644 (1994)
Oxidation of chromanones (1a-i) and 2-spiro-chromanones (1j-m) using [hydroxy(tosyloxy)iodo]benzene in refluxing acetonitrile as well as using ultrasound via dehydrogenation and 2,3-alkyl migration provides a convenient route for the synthesis of chromones (2a-i), tetrahydroxanthones (2j, k) and their higher homologues (2l, m). The ultrasound also enhances substantially the rate of above transformations.
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Exploiting a silver-bismuth hybrid material as heterogeneous noble metal catalyst for decarboxylations and decarboxylative deuterations of carboxylic acids under batch and continuous flow conditions
?tv?s, Sándor B.,Fül?p, Ferenc,Kónya, Zoltán,Kukovecz, ákos,Márton, András,Mészáros, Rebeka,Pálinkó, István,Szabados, Márton,Varga, Gábor
, p. 4685 - 4696 (2021/07/12)
Herein, we report novel catalytic methodologies for protodecarboxylations and decarboxylative deuterations of carboxylic acids utilizing a silver-containing hybrid material as a heterogeneous noble metal catalyst. After an initial batch method development, a chemically intensified continuous flow process was established in a simple packed-bed system which enabled gram-scale protodecarboxlyations without detectable structural degradation of the catalyst. The scope and applicability of the batch and flow processes were demonstrated through decarboxylations of a diverse set of aromatic carboxylic acids. Catalytic decarboxylative deuterations were achieved on the basis of the reaction conditions developed for the protodecarboxylations using D2O as a readily available deuterium source.
Visible Light-Promoted Selenylation/Cyclization of Enaminones toward the Formation of 3-Selanyl-4H-Chromen-4-Ones
Liu, Hao-Yang,Zhang, Jia-Rong,Huang, Guo-Bao,Zhou, Yi-Huan,Chen, Yan-Yan,Xu, Yan-Li
supporting information, p. 1656 - 1661 (2021/02/12)
A simple and efficient visible-light-promoted selenylation/cyclization of enaminones have been realized for the practical synthesis of 3-selanyl-4H-chromen-4-ones. This reaction is performed in the mild conditions, no transition metal catalyst or photocatalysts and no additional oxidants are required. In addition, the 3-selanyl-4H-chromen-4-ones could be easily converted to selanyl-functionalized pyrimidines by reacting with benzamidine substrates. (Figure presented.).
