Synthesis of Acyl Pyrroles via Palladium-Catalyzed Carbonylative Amination of Aryl and Alkenyl Iodides

Abstract

A palladium-catalyzed synthesis of acyl pyrroles from aryl and alkenyl iodides is reported. This carbonylative amination requires only atmospheric (balloon) pressure of carbon monoxide and proceeds with Pd(PPh(3))(4) and Pd-NHC catalysts. Aryl and heteroaryl iodides give the corresponding acyl pyrroles in good to excellent yields, while alkenyl iodides provide the corresponding acyl pyrroles in low to moderate yields.

Highly Efficient Aminocarbonylation of Iodoarenes at Atmospheric Pressure Catalyzed by a Robust Acenaphthoimidazolyidene Allylic Palladium Complex

“…Among them, the palladium-catalyzed aminocarbonylation reactions are less studied and consititute an indispensable highly regioselective methodology to synthesize amides, which broadly exist in bioactive drugs (Figure ), polymers, and natural products . Although some progress has been achieved along with the development of various catalysts containing phosphine ligands (Figure ), − their applicability is still hindered by the following aspects: (1) high catalyst loadings (usually 2–10 mol %), (2) high temperatures (100–150 °C in general), (3) high pressure of carbon monoxide (up to 180 psi), and (4) tedious handle steps are required to avoid oxidization of the highly air sensitive phosphines. Moreover, the most essential obstacle is that the activity of the catalysts toward oxidative addition of aryl halides is hindered by the strong bonding ability of CO (π acceptor) to the Pd center .…”

An Efficient Palladium-Catalysed Aminocarbonylation of Benzyl Chlorides

“…Our approach for obtaining suitable conditions to effect this transformation was to study the background alkylation with various solvents and bases that are commonly employed in aminocarbonylation reactions [6][7][8][9][10][11][12][13][14] with the intent of identifying those in which the undesired alkylation is slowest. This approach afforded a reasonable expectation that a viable method could be found by subsequent screening around these conditions to identify potential catalysts and optimise solvent, base and ligand.…”

“…5 Aminocarbonylation is a well-described and synthetically expedient method for the preparation of aryl amides from the corresponding aryl halide or pseudohalide and amine in the presence of carbon monoxide and a suitable catalyst. [6][7][8][9][10][11][12][13][14] Only a small number of examples have been reported for the aminocarbonylation of benzylic halides and those examples demonstrate the main challenge associated with overcoming the competing background alkylation of the amine and benzyl halide starting materials. This is frequently cited as justification of the development of alternate methods for the synthesis of 2-arylacetamides (Scheme 1).…”

Design and Development of Ligands for Palladium-Catalyzed Carbonylation Reactions

“…115b In the presence of complex 15b under 1 bar carbon monoxide, Orellana and co-workers accomplished the aminocarbonylation of aryl and alkenyl iodides with pyrrole in moderate to excellent yields (43-93%; Scheme 30, b). 120 Although the pressure of carbon monoxide was relatively low, 10 mol% catalyst loading had to be used in the protocol. Furthermore, other amines were not investigated.…”