Palladium-catalyzed aminocarbonylation of aryl iodides using aqueous ammonia

Supported palladium catalyzed aminocarbonylation of aryl iodides employing bench-stable CO and NH3 surrogates

A simple, efficient and phosphine free protocol for carbonylative synthesis of primary aromatic amides under polystyrene supported palladium (Pd@PS) nanoparticle (NP) catalyzed conditions has been demonstrated. Herein, instead of using two toxic and difficult to handle gases simultaneously, we have employed the solid, economical, bench stable oxalic acid as the CO source and ammonium carbamate as the NH3 source in a single pot reaction. For the first time, we have applied two non-gaseous surrogates simultaneously under heterogeneous catalyst (Pd@PS) conditions for the synthesis of primary amides using an easy to handle double-vial (DV) system. The developed strategy showed a good functional group tolerance towards a wide range of aryl iodides and afforded primary aromatic amides in good yields. The Pd@PS catalyst was easy to separate and can be recycled up to four consecutive runs with small loss in catalytic activity. We have successfully extended the scope of the methodology to the synthesis of isoindole-1,3-diones from 1,2-dihalobenzene, 2-halobenzoates and 2-halobenzoic acid following double and single carbonylative cyclization approaches.

Nitromethane as a nitrogen donor in Schmidt-type formation of amides and nitriles

The Schmidt reaction has been an efficient and widely used synthetic approach to amides and nitriles since its discovery in 1923. However, its application often entails the use of volatile, potentially explosive, and highly toxic azide reagents. Here, we report a sequence whereby triflic anhydride and formic and acetic acids activate the bulk chemical nitromethane to serve as a nitrogen donor in place of azides in Schmidt-like reactions. This protocol further expands the substrate scope to alkynes and simple alkyl benzenes for the preparation of amides and nitriles.

Application of γ-Valerolactone as an Alternative Biomass-Based Medium for Aminocarbonylation Reactions

γ-Valerolactone (GVL) was proposed as a renewable, nontoxic reaction medium with negligible vapor pressure for homogeneous Pd-catalyzed aminocarbonylation reactions. Iodobenzene as a model substrate and its 4-substituted derivatives were converted to the corresponding 2-ketocarboxamides with high conversions and chemoselectivities in γ-valerolactone. The effect of carbon monoxide pressure and reaction temperature on the conversion and selectivities were studied in the range 1-50 bar and 25-100 °C, respectively. The highest conversion and selectivity was achieved at 25 bar and 50 °C for iodobenzene in GVL for 24 h.

Selective Palladium-Catalyzed Aminocarbonylation of Olefins to Branched Amides

A general and efficient protocol for iso-selective aminocarbonylation of olefins with aliphatic amines has been developed for the first time. Key to the success for this process is the use of a specific 2-phosphino-substituted pyrrole ligand in the presence of PdX₂ (X=halide) as a pre-catalyst. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino-acid derivatives, to give the corresponding branched amides generally in good yields (up to 99 %) and regioselectivities (b/l up to 99:1).

Pd/C-catalyzed facile synthesis of primary aromatic amides by aminocarbonylation of aryl iodides using ammonia surrogates

Use of Pd/C as an efficient, phosphine free, heterogeneous and recyclable catalyst for one pot carbonylative synthesis of primary aromatic amides has been demonstrated.

Palladium on manganese ferrite: an efficient catalyst for one pot synthesis of primary amides from iodobenzene

Amidation of aryl iodide in one pot is reported using Pd–MnFe₂O₄ as a catalyst.