Convenient Processes for the Synthesis of Aromatic Ketones from Aryl Bromides and Carboxylic Anhydrides Using a Cobalt Catalysis

Abstract

The cross-coupling of various para- and meta-substituted aromatic bromides, mostly bearing sensitive moieties, with several carboxylic acid anhydrides is reported. This reaction can be carried out in two steps, by forming an aromatic organozinc reagent via cobalt catalysis in the first step, or even more interestingly in a single step, also by using a cobalt-based catalyst. The aromatic ketones are obtained by these new, mild, and convenient methods in 30-79% yields versus starting aryl bromide. Results are also disclosed that suggest the role played by cobalt species in the coupling of organozinc reagents with electrophiles could be similar to those of more commonplace transition metal complexes.

Unexpected stabilization of a simple cobalt(I) salt in acetonitrile at a glassy carbon electrode

“…Most of these syntheses involve a reactive cobalt(I) species which is generated in situ either by electrochemical [5][6][7][8][9] or chemical [10,11] reduction of the corresponding cobalt(II) salt.…”

MgCl2‐beschleunigte Additionen von funktionalisierten Organozinkreagentien an Aldehyde, Ketone und Kohlendioxid

“…[1] Ihre moderate Reaktivität gegenüber Elektrophilen kann durch Transmetallierungen mit katalytischen Mengen verschiedener Über-gangsmetallkomplexe von Pd, [2] Ni, [3] Cu, [4] Fe, [5] Co [6] und anderen Metallsalzen [7] stark erhöht werden. Jedoch sind solche Transmetallierungen für Reaktionen mit Ketonen oder Aldehyden weniger geeignet.…”

Diphenylzinc

“…Anhydrides have recently garnered attention as competent acylating agents in metal mediated reactions. 32a, 33 An alkylative (and arylative) desymmetrization of bicyclic anhydrides in the presence of a nickel (or palladium) catalyst providing keto acids was disclosed in good yields under mild conditions. 34 For example, the cis-hexahydrophthalic anhydride can react with Ph 2 Zn to furnish the corresponding cyclic keto acid in 88% yield when using Pyphos as a ligand (eq 26).…”