89338-08-9Relevant academic research and scientific papers
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.
Efficient Synthesis of Dimeric Oxazoles, Piperidines and Tetrahydroisoquinolines from N-Substituted 2-Oxazolones
He, Yun,Agarwal, Piyush K.,Kiran, I. N. Chaithanya,Yu, Ruocheng,Cao, Bei,Zou, Cheng,Zhou, Xinghua,Xu, Huacheng,Xu, Biao,Zhu, Lei,Lan, Yu,Nicolaou
supporting information, p. 7696 - 7701 (2016/06/09)
A mild and practical method for the construction of heterocycles from N-substituted 2-oxazolones through cascade, BF3·Et2O/H2O-catalyzed reactions involving iminium ion generation and trapping by external or internal olefinic and aryl moieties is described. Mechanistic and computational studies revealed the strong protic acid HBF4as the initiating catalyst for these cascade reactions. Providing access to novel molecular diversity, these processes may facilitate chemical biology studies, drug discovery efforts and natural products synthesis.
