General Copper-Catalyzed Coupling of Alkyl-, Aryl-, and Alkynylaluminum Reagents with Organohalides

作者：Shrestha Bijay; Thapa Surendra; Gurung Santosh K; Pike Ryan A S; Giri Ramesh

来源：Journal of Organic Chemistry, 2016, 81(3): 787-802.

DOI：10.1021/acs.joc.5b02077

We report the first example of a very general Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. The reactions proceed for the couplings of alkyl-, aryl-, and alkynylaluminum reagents with aryl and heteroaryl halides and vinyl bromides, affording the cross-coupled products in good to excellent yields. Both primary and secondary alkylaluminum reagents can be utilized as organometallic coupling partners. These reactions are not complicated by beta-hydride elimination, and as a result rearranged products are not observed with secondary alkylaluminum reagents even for couplings with heteroaryl halides under "ligand-free" conditions. Radical clock experiment with a radical probe and relative reactivity study of Ph3Al with two haloarenes, 1-bromonaphthalene and 4-chlorobenzonitrile, having two different redox potentials indicates that the reaction does not involve free aryl radicals and radical anions as intermediates. These results combined with the result of the Hammett plot obtained by reacting Ph(3)A1 with iodoarenes containing p-H, p-Me, p-F, and p-CF3 substituents, which shows a linear curve (R-2 = 0.99) with a p value of +1.06, suggest that the current transformation follows an oxidative addition reductive elimination pathway.

• 出版日期2016-2-5