Reductive Decarboxylative Alkynylation of
<i>N</i>
‐Hydroxyphthalimide Esters with Bromoalkynes
作者:Liangbin Huang、Astrid M. Olivares、Daniel J. Weix
DOI:10.1002/anie.201706781
日期:2017.9.18
A new method for the synthesis of terminal and internal alkynes from the nickel‐catalyzed decarboxylative coupling of N‐hydroxyphthalimide esters and bromoalkynes is presented. This reductivecross‐electrophilecoupling is the first to use a C(sp)−X electrophile, and appears to proceed via an alkynylnickel intermediate. The internal alkyne products are obtained in yields of 41–95 % without the need
The easily accessible haloalkynes can be converted to (Z)-2-halo-1-iodoalkenes in high yields with excellent regio- and stereoselectivity. The method shows good functional group compatibility. The resulting products could find broad applications.
Regio- and Stereoselective Synthesis of 1,2-Dihaloalkenes Using In-Situ-Generated ICl, IBr, BrCl, I2, and Br2
作者:Xiaojun Zeng、Shiwen Liu、Yuhao Yang、Yi Yang、Gerald B. Hammond、Bo Xu
DOI:10.1016/j.chempr.2020.03.011
日期:2020.4
2-trans-dihalogenation of alkynes with an unprecedented substrate scope and exclusive regio- and stereoselectivity. This versatile dihalogenation system—a combination of NX1S electrophile and alkali metal halide (MX2) in acetic acid—is applicable for diverse categories of alkynes (electron-rich or poor alkynes, internal and terminalalkynes, or heteroatoms such as O-, N-, S-substituted alkynes). The hydrogen
我们描述了炔烃的无催化剂的1,2-反式二卤代反应,具有空前的底物范围和排他性和立体选择性。这种多功能的二卤化系统-NX 1 S亲电试剂和乙酸中的碱金属卤化物(MX 2)的组合-适用于各种类型的炔烃(富电子或弱炔烃,内部和末端炔烃,或杂原子,例如O- ,N-,S-取代的炔烃)。氢键供体溶剂乙酸对于就地生成X 1 X 2亲电试剂(包括ICl,IBr,BrCl,I 2和Br 2)是必不可少的。
Metal-Free Synthesis of Highly Substituted Pyridines by Formal [2+2+2] Cycloaddition under Mild Conditions
The synthesis of pyridines through direct intermolecular cycloaddition of alkynes and nitriles is a contemporary challenge in organic synthesis. A Brønsted acid mediated formal [2+2+2] cycloaddition of heteroalkynes and nitriles was developed that proceeds under mild conditions. This constitutes a modular approach to highly substituted pyridine cores.
Highly Selective <i>Syn</i>
Addition of 1,3-Diones to Internal Ynamides Catalyzed by Zinc Iodide
作者:Rémi Plamont、Lionel V. Graux、Hervé Clavier
DOI:10.1002/ejoc.201701690
日期:2018.3.22
used as nucleophiles to perform additions to ynamides, highly selective hydroalkoxylation of internal ynamides is now described herein. Several catalytic systems were compared to carry out this transformation including transition metal-based catalysts or Lewis acids. ZnI2 was found to be both very active and highly selective giving only E adducts through a syn addition. Scope and limits investigation