Cut and paste! A Cu‐catalyzed aromaticCHcyanation with acetonitrile as the nitrile source by CCNcleavage has been developed (see scheme; TMEDA=N,N,N′,N′‐tetramethylethylenediamine). The reaction is catalytic in copper, and it is found that using (Me3Si)2 as an additive plays a critical role in promoting CCNcleavage and enhancing the reaction rate.
A chelation-assistedpalladium-catalyzed ortho-cyanation of the sp2 C−H bond by CuCN provided aromatic nitriles in moderate to good yields. Notably, the reaction could be conducted on a 10 mmol scale. The key intermediate of the natural product of Menispermum dauricum DC was concisely synthesized by the procedure. This new approach represents an exceedingly practical method for the synthesis of aromatic
Co(III)-Catalyzed C–H Activation/Formal S<sub>N</sub>-Type Reactions: Selective and Efficient Cyanation, Halogenation, and Allylation
作者:Da-Gang Yu、Tobias Gensch、Francisco de Azambuja、Suhelen Vásquez-Céspedes、Frank Glorius
DOI:10.1021/ja511011m
日期:2014.12.24
The first cobalt-catalyzed cyanation, halogenation, and allylation via C-Hactivation have been realized. These formal SN-type reactions generate valuable (hetero)aryl/alkenyl nitriles, iodides, and bromides as well as allylated indoles using a bench-stable Co(III) catalyst. High regio- and mono-selectivity were achieved for these reactions. Additionally, allylation proceeded efficiently with a turnover