Chemoselective sp2-sp3 Cross-Couplings: Iron-Catalyzed Alkyl Transfer to Dihaloaromatics
摘要:
The chemoselective functionalization of a range of dihaloaromatics with methyl, cyclopropyl, and higher alkyl Grignard reagents via iron-catalyzed cross-coupling is described. The site selectivity of C-X (X = halogen) activation is determined by factors such as the position of the halogen on the ring, the solvent, and the nucleophile. A one-pot protocol for the chemoselective synthesis of mixed dialkyl heterocycles is achieved solely employing iron catalysis.
Ligand-Free Copper-Catalyzed Negishi Coupling of Alkyl-, Aryl-, and Alkynylzinc Reagents with Heteroaryl Iodides
作者:Surendra Thapa、Arjun Kafle、Santosh K. Gurung、Adam Montoya、Patrick Riedel、Ramesh Giri
DOI:10.1002/anie.201502379
日期:2015.7.6
Reported herein is an unprecedented ligand‐free copper‐catalyzed cross‐coupling of alkyl‐, aryl‐, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzincreagents with heteroaryl iodides without rearrangement. An elevated temperature (100 °C) is required for aryl–heteroaryl and alkynyl–heteroaryl couplings