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。
Water-Soluble Hypervalent Iodine(III) Having an I–N Bond. A Reagent for the Synthesis of Indoles
A readily accessible and bench-stable water-soluble hypervalent iodine(III) reagent (phenyliodonio)sulfamate (PISA) with an I–N bond was synthesized, and its structure was characterized by X-ray crystallography. With PISA, various indoles were synthesized via C–H amination of 2-alkenylanilines involving an aryl migration/intramolecular cyclization cascade with excellent regioselectivity in aqueous
The synthesis of sulfonated 4<i>H</i>-3,1-benzoxazines <i>via</i> an electro-chemical radical cascade cyclization
作者:Tian-Jun He、Wei-Qiang Zhong、Jing-Mei Huang
DOI:10.1039/c9cc09551a
日期:——
A new route for the synthesis of sulfonated 4H-3,1-benzoxazines has been accomplished by electrochemical radical cascade cyclizations of styrenyl amides with sulfonylhydrazines. This process demonstrates a wide substrate scope with diverse functional group compatibility under metal- and external oxidant-free conditions at ambient temperature.
Treatment of Olefinic Amides with NBS in Water: Synthesis of Monobromo- and Multibromobenzoxazines
作者:Xu Zhang、Wen-Bin Cao、Xiao-Ping Xu、Shun-Jun Ji
DOI:10.1055/s-0037-1610724
日期:2019.10
Abstract Treatment of olefinic amides with N-bromosuccinimide (NBS) in water is reported. Monobromobenzoxazines were mainly formed at room temperature, while at 80 °C multibromobenzoxazines were preferentially generated. Mechanism studies showed that the reaction might proceed via a cascade of electrophilic addition at the C=C bond followed by electrophilic substitution at the aromatic ring. No additives
Redox-neutral photocatalytic cyanomethylation/cyclization cascade of olefinic amides: Access to cyanomethylated benzoxazines
作者:Liang Liu、Yan-Hong He、Zhi Guan
DOI:10.1016/j.tet.2019.130716
日期:2019.12
A visible-light-induced photocatalytic cyanomethyl radical addition/intramolecular cyclization cascade reaction of olefinic amides has been developed under mild conditions. This reaction provides a novel method for the synthesis of various cyanomethyl-containing benzoxazines, which are useful pharmaceutical framework. The method exhibits good functional group tolerance and a wide range of substrate