Catalyst-Free Intramolecular Oxidative Cyclization of N-Allylbenzamides: A New Route to 2,5-Substituted Oxazoles
摘要:
A catalyst-free intramolecular oxidative cyclization reaction of N-allylbenzamides has been developed to prepare 2,5-disubstituted oxazoles with good yields. This reaction gives an efficient synthetic strategy to form an oxazole nucleus directly from easily accessible substrates under temperate conditions.
Electrochemical oxidative radical cascade cyclization of olefinic amides and thiophenols towards the synthesis of sulfurated benzoxazines, oxazolines and iminoisobenzofurans
containing N and O are important structures in pharmaceuticals, agrochemicals and functional molecules. The synthesis of these compounds usually requires complex substrates and harsh reaction conditions. Herein, we introduce a mild and efficient electrochemical oxidative strategy to construct benzoxazines, oxazolines and iminoisobenzofurans without the requirement of a transition-metal catalyst and an
含 N 和 O 的杂环是药物、农用化学品和功能分子中的重要结构。这些化合物的合成通常需要复杂的底物和苛刻的反应条件。在此,我们引入了一种温和有效的电化学氧化策略来构建苯并恶嗪、恶唑啉和亚氨基异苯并呋喃,而无需过渡金属催化剂和外部氧化剂。在一个简单的未分开的细胞中,各种烯酰胺和苯硫酚/二硒化物反应生成 69 个硫醇化和硒化杂环的例子,产率高达 83%。此外,这种自由基级联反应为一步构建 C-S/C-Se 和 C-O 键提供了一种简便的方法。
Amide Synthesis by Nickel/Photoredox‐Catalyzed Direct Carbamoylation of (Hetero)Aryl Bromides
作者:Nurtalya Alandini、Luca Buzzetti、Gianfranco Favi、Tim Schulte、Lisa Candish、Karl D. Collins、Paolo Melchiorre
DOI:10.1002/anie.202000224
日期:2020.3.23
Herein, we report a one‐electron strategy for catalytic amide synthesis that enables the direct carbamoylation of (hetero)aryl bromides. This radical cross‐coupling approach, which is based on the combination of nickel and photoredox catalysis, proceeds at ambient temperature and uses readily available dihydropyridines as precursors of carbamoyl radicals. The method's mild reaction conditions make
Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines
作者:Felix Scheidt、Christian Thiehoff、Gülay Yilmaz、Stephanie Meyer、Constantin G Daniliuc、Gerald Kehr、Ryan Gilmour
DOI:10.3762/bjoc.14.88
日期:——
Herein, we describe a catalytic fluorooxygenation of readily accessible N-allylcarboxamides via an I(I)/I(III) manifold to generate 2-oxazolines containing a fluoromethyl group. Catalysis is conditional on the oxidation competence of Selectfluor®, whilst HF serves as both a fluoride source and Brønsted acid activator. The C(sp3)-F bond of the mono-fluoromethyl unit and the C(sp3)-O bond of the ring
We report a new air‐stable PdI dimer, [Pd(μ‐I)(PCy2tBu)]2, which triggers E‐selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapidC−Ccoupling (alkylation and arylation) at roomtemperature in a modular and triply selective fashion of aromatic C−Br, C−OTf/OFs, and
我们报告了一种新的空气稳定的Pd I二聚体[Pd(μI)(PCy 2 t Bu)] 2,它在存在多个官能团且具有完全耐受性的情况下触发E-选择性烯烃向酰胺和苯乙烯衍生物的迁移空气 同一二聚体还可以在室温下以模块化和三重选择性的方式在聚(假)卤代芳烃中以芳族C-Br,C-OTf / OF和C-Cl键的形式快速触发C-C偶联(烷基化和芳基化)在具有邻位C-OTf的取代基的底物上显示出比以前的Pd I二聚体更好的活性。
Flow electrochemistry: a safe tool for fluorine chemistry
作者:Bethan Winterson、Tim Rennigholtz、Thomas Wirth
DOI:10.1039/d1sc02123k
日期:——
The heightened activity of compounds containing fluorine, especially in the field of pharmaceuticals, provides major impetus for the development of new fluorination procedures. A scalable, versatile, and safe electrochemical fluorination protocol is conferred. The strategy proceeds through a transient (difluoroiodo)arene, generated by anodic oxidation of an iodoarene mediator. Even the isolation of
含氟化合物的活性增强,特别是在制药领域,为新氟化工艺的开发提供了主要动力。提供了一种可扩展、通用且安全的电化学氟化方案。该策略通过碘芳烃介体的阳极氧化产生瞬态(二氟碘)芳烃来进行。甚至二氟化碘( III )的分离也很容易,因为电解是在没有其他试剂的情况下进行的。通过将电解步骤与流动中的下游反应耦合,以高产率实现了广泛的高价碘介导的反应,超越了间歇化学的限制。(二氟碘)芳烃有毒且化学不稳定,因此不间断生成和立即流动使用非常有利。高流速使生产率高达 834 mg h -1,同时大大缩短了反应时间。集成到全自动机器和在线淬火是减少氢氟酸使用带来的危害的关键。