2757-04-2Relevant articles and documents
Microwave accelerated the solvent-free synthesis of 4-aryl-3,4-dihydrocoumarin via the tandem reaction of cinnamic acids with phenols catalyzed by Amberlyst 15 resin
Le, Huu-Phuoc,Duong, Cong-Thang,Nguyen, Xuan-Triet,Luu, Thi Xuan Thi
, p. 2187 - 2203 (2021/07/02)
Amberlyst 15 resin supported the tandem reaction of cinnamic acids with phenols under solvent-free reaction condition has been introduced to afford 4-aryl-3,4-dihydrocoumarin (neoflavanone) derivatives. The efficiency of solid acidic sulfonic resin (A-15) has been illustrated in two reaction activation methods such as microwave irradiation and conventional heating. The important roles of Amberlyst 15 have been emphasized strongly through the high yields of 4-aryl-3,4-dihydrocoumarin in the shorter time under the assistance of microwave irradiation than of conventional heating, and its high recovery and reusability for six catalyst runs. The original catalyst as well as the recycled catalyst were characterized by XRD and FE-SEM to study the correlation of the surface of reused catalyst and its recyclability.
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.
Photoinduced Oxidative Alkoxycarbonylation of Alkenes with Alkyl Formates
Tang, Wan-Ying,Chen, Ling,Zheng, Ming,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
supporting information, p. 3939 - 3943 (2021/05/26)
A photoinduced oxidative alkoxycarbonylation of alkenes initiated by intermolecular addition of alkoxycarbonyl radicals has been demonstrated. Employing alkyl formates as alkoxycarbonyl radical sources, a range of α,β-unsaturated esters were obtained with good regioselectivity and E selectivity under ambient conditions.