Merging Photoredox PCET with Ni-Catalyzed Cross-Coupling: Cascade Amidoarylation of Unactivated Olefins
作者:Shuai Zheng、Álvaro Gutiérrez-Bonet、Gary A. Molander
DOI:10.1016/j.chempr.2018.11.014
日期:2019.2
integration of amidylradicals with cross-coupling chemistry opens new avenues for reaction design. However, the lack of efficient methods for the generation of such radical species has prevented many such transformations from being brought to fruition. Herein, the amidoarylation of unactivated olefins by a cascade processfrom non-functionalized amides is reported by merging, for the first time, photoredox
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 siteselectivity and functional group
脂肪族催化脱氢 (CDA) 在有机合成中的价值在很大程度上仍未得到充分探索。已知的均相 CDA 系统通常需要使用牺牲氢受体(或氧化剂)、贵金属催化剂和苛刻的反应条件,因此将大多数现有方法限制为非或低官能化烷烃的脱氢。在这里,我们描述了一种可见光驱动的双催化剂系统,该系统由廉价的有机光氧化还原和贱金属催化剂组成,用于室温、无受体 CDA (Al-CDA)。该过程由光激发的 2-氯蒽醌引发,涉及脂肪族的 H 原子转移 (HAT) 形成烷基自由基,然后与钴肟反应生成烯烃和 H 2. 这种操作简单的方法能够将容易获得的化学原料直接脱氢成多种官能化的烯烃。例如,我们首次证明了硫醚和酰胺在无氧化剂条件下分别脱饱和为烯基硫醚和烯酰胺。此外,14 种生物相关分子和药物成分的后期脱氢和合成说明了该系统卓越的位点选择性和官能团耐受性。机理研究揭示了双重 HAT 过程,并提供了对反应性和位点选择性起源的见解。
Iodine(V) Reagents in Organic Synthesis. Part 3. New Routes to Heterocyclic Compounds via <i>o</i>-Iodoxybenzoic Acid-Mediated Cyclizations: Generality, Scope, and Mechanism
作者:K. C. Nicolaou、P. S. Baran、Y.-L. Zhong、S. Barluenga、K. W. Hunt、R. Kranich、J. A. Vega
DOI:10.1021/ja012126h
日期:2002.3.1
The discovery and development of the o-iodoxybenzoic acid (IBX) reaction with certain unsaturated N-aryl amides (anilides) to form heterocycles are described. The application of the method to the synthesis of delta-lactams, cyclic urethanes, hydroxy amines, and amino sugars among other important building blocks and intermediates is detailed. In addition to the generality and scope of this cyclization
作者:Shuai Zheng、Shuo-Qing Zhang、Borna Saeednia、Jiawang Zhou、Jessica M. Anna、Xin Hong、Gary A. Molander
DOI:10.1039/d0sc01459a
日期:——
The selective 1,2-aminoacylation of olefins provides opportunities for the rapid construction of nitrogen-containing molecules. However, the lack of CO-free acylation reactions has limited their application. By using photoredox proton-coupled electron transfer (PCET)/Ni dual-catalysis, a highly regio- and diastereoselective amidoacylation of unactivated olefins has been developed. Various acyl electrophiles
The unusual behavior of hypervalent iodine reagents, Dess - Martin periodinane and IBX, with an array of anilides leads to the formation of complex heterocycles in only one synthetic operation (see scheme). Furthermore, the substrates for these transformations are available in one step from readily available commercial building blocks. The mechanism by which these periodinanes interact with anilides