The Rh‐catalyzeddirectcarboxylation of alkenyl C−Hbonds was achieved by using pyrazole as a removable directing group. In the presence of 5 mol% RhCl3 ⋅ 3H2O, 6 mol% P(Mes)3, and 2 equiv. of AlMe2(OMe), the alkenyl C−H bond of various alkenylpyrazoles was directly carboxylated in good yields under CO2 atmosphere. Furthermore, several useful transformations of the pyrazole moiety of the product were
contrast to the selectivedoubleaddition, the corresponding singleaddition of aliphatic and aromatic terminal alkynes exclusively proceeded in the presence of a catalytic amount of silver nitrate. Internal alkynes also participated in the singleaddition reaction with the aid of silver triflate as a catalyst. The notable feature of this protocol is the utilization of an addition reaction being optimal
A protocol for the synthesis of terminal N-vinylazoles from aromatic aldehydes, DMSO, and azoles has been reported. In this strategy, DMSO was involved in the construction of the C=C bond as a terminal carbon synthon. Both aromatic aldehydes and azoles could be well tolerated and give the corresponding terminal N-vinylazoles in 52–91% yields. Based on preliminary experiments, a plausible mechanism
Rhodium(III)-Catalyzed Directed C–H Coupling with Methyl Trifluoroacrylate: Diverse Synthesis of Fluoroalkenes and Heterocycles
作者:Tian-Jun Gong、Meng-Yu Xu、Shang-Hai Yu、Chu-Guo Yu、Wei Su、Xi Lu、Bin Xiao、Yao Fu
DOI:10.1021/acs.orglett.7b03677
日期:2018.2.2
An example of Rh-catalyzed C–H activation with methyl trifluoroacrylate for the synthesis of fluoroolefins and heterocycles (benzoindolizines) is reported. The types of products were determined by the directing group. The benzoindolizines and fluoroolefins were obtained by using pyridine and pyrazole as the directing group, correspondingly. These transformations present a number of advantages, such
Cobalt(III)-Catalyzed Aryl and Alkenyl CH Aminocarbonylation with Isocyanates and Acyl Azides
作者:Jie Li、Lutz Ackermann
DOI:10.1002/anie.201501926
日期:2015.7.13
cobalt(III) catalyst that shows high functional group tolerance. The CH functionalization occurred with excellent chemo‐, site‐, and diastereoselectivity and enabled step‐economical reactions with isocyanates or acyl azides.