Palladium-Catalyzed Highly Chemoselective Intramolecular C-H Aminocarbonylation of Phenethylamines to Six-Membered Benzolactams

Palladium-catalyzed regioselective carbonylation of 2-amino-2,3-diphenylpropanoate to 5/6-membered benzolactams

Five/six-membered benzolactams are significant blocks in both organic and medicinal chemistry. Achieving 5/6-membered benzolactams from the same starting compound under varying reaction conditions presents a significant challenge. Herein, palladium-catalyzed free amine-oriented regioselective C-H activations/carbonylations mediated by hexacarbonylmolybdenum, leading to diverse sizes of benzolactams, respectively, have been developed. Six-membered dihydroisoquinolinones can be obtained selectively in acetic acid using benzoquinone as an oxidant. While unfavorable five-membered isoindolinones were formed in the presence of Cu(II) as an oxidant and dihydrooxazole ligands in 1,2-dichlorobenzene. The substituents on the phenyl ring also had a great influence on the regioselectivity of the reaction. In addition, an asymmetric version of the reaction has also been attempted preliminarily.

Palladium-catalyzed dehydrogenative C–H cyclization for isoindolinone synthesis

In this paper Pd-catalyzed intramolecular dehydrogenative C(sp³)–H amidation for the synthesis of isoindolinones is described. This method features the use of a Pd/C catalyst and the addition of a stoichiometric amount of oxidant is not necessary. A mechanistic study suggested the possible formation of H₂ gas during the reaction.

Pd-catalyzed intramolecular dehydrogenative C(sp³)–H amidation for the synthesis of isoindolinones was developed. Use of Pd/C as a catalyst enables the desired cyclization to proceed smoothly without adding any stoichiometric oxidants.

RhIII -Catalyzed Double Dehydrogenative Coupling of Free 1-Naphthylamines with α,β-Unsaturated Esters

The Rh^III -catalyzed, consecutive double C-H oxidative coupling of free 1-naphthylamine and α,β-unsaturated esters through C-H/C-H and C-H/N-H bonds is reported. The one step reaction leads to the formation of biologically important alkylidene-1,2-dihydrobenzo[cd]indoles scaffolds. This efficient process is much more synthetically convenient and useful than others because the starting materials, such as 1-naphthylamine derivatives are readily available and the free amine serves as a directing group.

Pd/Cu Cocatalyzed Oxidative Tandem C-H Aminocarbonylation and Dehydrogenation of Tryptamines: Synthesis of Carbolinones

The Pd/Cu cocatalyzed oxidative tandem C-H aminocarbonylation and dehydrogenation was developed, affording carbolinones with molecular oxygen as the terminal oxidant. Natural product strychnocarpine and its derivatives were prepared conveniently using this strategy.

Palladium(II)-Catalyzed C(sp2)-H Carbonylation of Sterically Hindered Amines with Carbon Monoxide

A palladium-catalyzed, amine-directed C(sp²)-H carbonylation of α,α-disubstituted benzylamine under 1 atm of CO for the facile synthesis of sterically hindered benzolactam has been developed. The key to success is the use of 2,2,6,6-tetramethyl-1-piperidinyloxy as the crucial sole oxidant. The synthetic utility of this transformation has been demonstrated by the first concise synthesis of the natural product spiropachysin-20-one.

Nitroarenes as the Nitrogen Source in Intermolecular Palladium-Catalyzed Aryl C-H Bond Aminocarbonylation Reactions

A three-component palladium-catalyzed aminocarbonylation of aryl and heteroaryl sp² C-H bonds using nitroarenes as the nitrogen source was achieved using Mo(CO)₆ as the reductant and origin of the CO. This intermolecular C-H bond functionalization does not requires any exogenous ligand to be added, and our mechanism experiments indicate that the palladacycle catalyst serves two roles in the aminocarbonylation reaction: reduce the nitroarene to a nitrosoarene and activate the sp² C-H bond.

Palladium-Catalyzed Intramolecular Cross-Dehydrogenative Coupling: Synthesis of Fused Imidazo[1,2-a]pyrimidines and Pyrazolo[1,5-a]pyrimidines

A palladium-catalyzed intramolecular dehydrogenative coupling reaction was developed for the synthesis of fused imidazo[1,2-a]pyrimidines and pyrazolo[1,5-a]pyrimidines. The developed protocol provides a practical approach for the synthesis of biologically important substituted pyrimidines from easily available substrates, with a broad substrate scope under mild reaction conditions.