Pd-Catalyst Containing a Hemilabile P,C-Hybrid Ligand in Amino Dicarbonylation of Aryl Halides for Synthesis of α-Ketoamides

Abstract

The amino dicarbonylation of aryl halides affording α-ketoamides with Pd catalysts is highly dependent on the stereoelectronic properties of the involved ligands. Ionic diphosphine ligand L4 can serve as precursor of a hemilabile P,C (phosphine, carbene)-hybrid ligand to form a stable Pd(II)complex, Pd-L4. In contrast, analogues L1−L3 with a similar 1-(thiophen-3-yl)-benzimidazolyl skeleton behave as typical (mono/ di)phosphines. The catalytic system resulting from the complexation of PdCl 2 (MeCN) 2 and L4 exhibits good catalytic performance in terms of aryl iodides conversion (81−95%) and αketoamide selectivity (80−91%), as well as the available recyclability in the RTIL of [Bpy]BF 4 . The in situ FT-IR analysis reveals that the PdCl 2 (MeCN) 2 −L4 catalytic system favors the amino dicarbonylation toward α-ketoamides according to the proposed mechanism of cycle I, which involves two independent COinsertion steps.

Synthesis of N-[1-(2-Acetyl-4,5-dimethoxyphenyl)propan-2-yl]benzamide and Its Copper(II) Complex

“…New zirconium complexes with β-ketoester and β-ketoamide having potential to serve as precursors for MOCVD of ZrO 2 thin films [20]. A series of metal complexes of α-ketoamide were synthesized and their composition and structure with palladium was studied [21,22]. Recently, we presented the synthesis and characterization of a new Pd(II) and Zn(II) complexes of N-substituted-4,5-dimethoxyphenylethyl-2-arylketoamides [23], as well as the crystal structure of N-(2-benzoyl-4,5-dimethoxyphenethyl)-2phenylacetamide [24].…”

Radical Cross-Coupling Reaction Based on Hydrogen Atom Abstraction of DMF and Decarboxylation of α-Ketoacid under Electricity

“…The designed reaction would provide a new avenue for the synthesis of α-ketoamides, which are not only a kind of highly valuable compound with biological and pharmaceutical activity but also widely applied as building blocks for versatile reactions. − Thus, many strategies for the synthesis of α-ketoamides were developed, such as the catalytic coupling reaction in the presence − or absence of metal, − radical-type reactions in the presence of peroxide or persulfide, , the electrochemical cross-dehydrogenation coupling of α-keto aldehydes with amines, etc. − These developed strategies often suffer from the requirement of metal or other catalysts, dangerous peroxides, or special and expensive chemical reagents. In contrast, the designed electrochemical preparation of α-ketoacid via the acyl radical–acyl radical coupling reaction is safe, simple, and inexpensive.…”

Multiple-Functional Diphosphines: Synthesis, Characterization, and Application to Pd-Catalyzed Alkoxycarbonylation of Alkynes

“…Later on, universal applications of phosphine ligands in alkoxycarbonylation of alkynes to warrant the activity, selectivity, and stability of Pd catalysts developed rapidly. − It was found that 1,4-bis­(diphenylphosphino)­butane (dppb), , triphenylphosphine, − 1,2-bis­(ditert-butylphosphinomethyl)­benzene (BDTBPMB), − and 2,2,-bis­(diphenylphosphino)-1,1-binaphthyl (BINAP) are well-known phosphines to improve Pd-catalyzed carbonylation. More recently, many N,P hybrid ligands with hemilability − have been reported in the literature, ,,− as shown in Scheme . Moreover, the specific effects of some reported ligands on alkoxycarbonylation of phenylacetylene have been summarized in Table S1 in the Supporting Information.…”