Stereoselective Synthesis of Trisubstituted Alkenes through Sequential Iron-Catalyzed Reductive<i>anti</i>-Carbozincation of Terminal Alkynes and Base-Metal-Catalyzed Negishi Cross-Coupling
作者:Chi Wai Cheung、Xile Hu
DOI:10.1002/chem.201504049
日期:2015.12.7
stereoselective synthesis of trisubstituted alkenes is challenging. Here, we show that an iron‐catalyzed anti‐selective carbozincation of terminal alkynes can be combined with a base‐metal‐catalyzed cross‐coupling to prepare trisubstituted alkenes in a one‐pot reaction and with high regio‐ and stereocontrol. Cu‐, Ni‐, and Co‐based catalytic systems are developed for the coupling of sp‐, sp2‐, and sp3‐hybridized
Trapping Reactions of Benzynes Initiated by Intramolecular Nucleophilic Addition of a Carbonyl Oxygen to the Electrophilic Aryne
作者:Bhavani Shankar Chinta、Sahil Arora、Thomas R. Hoye
DOI:10.1021/acs.orglett.1c04110
日期:2022.1.14
We describe here reactions in which a carbonyl oxygen atom initiates cascade reactions by nucleophilic attack on a covalently attached benzyne. The benzynes are produced by thermal cyclization of triynes via hexadehydro-Diels–Alder reaction. The initially produced oxocarbenium/aryl carbanionic zwitterion is protonated in situ by an external protic nucleophile (NuH) of appropriate acidity. The resulting
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