Copper-Catalyzed Cross-Dehydrogenative Coupling ofN-Iminoquinolinium Ylides with Secondary Amines

Recent synthetic strategies for N-arylation of pyrrolidines: a potential template for biologically active molecules

The chemistry of nitrogen-containing heterocyclic compounds has been a multifaceted area of research for an extended period due to their varied therapeutic and biological significance. N-Aryl pyrrolidine formed by condensation of aryl group with nitrogen atom of pyrrolidine is present in a wide array of compounds. Various significant activities shown by N-arylated pyrrolidine include anti-Alzheimer, antihypoxic, anticancer, plant activator, analgesic effect, and hepatitis C inhibitor. This review summarizes different synthetic approaches, e.g., transition-metal catalyzed and transition-metal-free synthesis, decarboxylation reaction, reductive amination, nucleophilic cyclization, Ullmann-Goldberg amidation, Buchwald-Hartwig reaction, Chan-Evans-Lam coupling, addition to benzyne, multistep reaction, green synthesis, rearrangement reaction, and multicomponent reaction, to afford the derivatives of N-aryl pyrrolidine. It encompasses synthetic strategies documented from 2015 to 2023.

Oxidative Nickel-Catalyzed ortho-C-H Amination of (Iso)quinolines with Alicyclic Amines Directed by a Sacrificial N-Oxide Group

Transition metal (TM)-catalyzed direct amination of C-H bonds on free or fused pyridine (Py) rings with free amines still remains scarce because amines and the Py ring tend to adopt a nonproductive N-bound coordination with many TMs, leading to a significant decrease of catalytic reactivity. We herein disclose a nickel-catalyzed and a sacrificial N-oxide group directed oxidative coupling of (iso)quinolyl C-H bonds and alicyclic amines, which furnishes bioimportant amino(iso)quinolines efficiently and selectively in a single step. Noteworthy, this protocol avoids the use of aggressive reactants and very strong bases usually required when aminating on nonoxidized Py rings.

Rhodium(iii)-catalyzed C–H activation/annulation of N-iminopyridinium ylides with alkynes and diazo compounds

Rh(iii)-Catalyzed C–H activation/annulation of N-iminopyridinium ylides with alkynes and diazo compounds has been realized for the synthesis of isoquinolones and isocoumarins.

A mild and metal-free synthesis of 2- and 1-alkyl/aryl/dialkyl-aminoquinolines and isoquinolines

A simple synthetic strategy has been developed for the synthesis of 2- and 1-alkyl/aryl/dialkylaminoquinolines and isoquinolines from the easily available quinoline and isoquinoline-N-oxides, different amines, triflic anhydride as activating agent and acetonitrile as solvent in a one-pot reaction under metal-free conditions at 0 °C to room temperature.

3d Transition Metals for C-H Activation

C-H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C-H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C-H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C-H activation until summer 2018.

Catalyst and Additive-Free Diastereoselective 1,3-Dipolar Cycloaddition of Quinolinium Imides with Olefins, Maleimides, and Benzynes: Direct Access to Fused N,N'-Heterocycles with Promising Activity against a Drug-Resistant Malaria Parasite

A convenient and eco-friendly synthesis of various fused N-heterocyclic compounds through catalyst and additive-free 1,3 dipolar cycloadditions of quinolinium imides with olefins, maleimides, and benzynes in excellent yields and diastereoselectivities is reported. The thermally controlled diastereoselective [3 + 2] cycloaddition reaction between quinolinium imides and olefins provided cis-isomers at low temperature and trans-isomers at high temperature. A reaction between quinolinium imides with substituted maleimides gave four-ring-fused N-heterocyclic compounds in high yields as a single diastereomer. The aryne precursors also provided four-ring-fused N,N'-heterocyclic compounds in high yields. The in vitro antiplasmodial activity of selected molecules revealed that this class of molecules possesses potential for ongoing studies against malaria.

Direct α-C-H amination using various amino agents by selective oxidative copper catalysis: a divergent access to functional quinolines

Herein, we present, for the first time, direct dehydrogenative α-C-H amination of tetrahydroquinolines (THQs) using various amino agents by selective aerobic copper catalysis, which enables divergent access to 2-aminoquinolines, the core structures of numerous functional products. In which, the catalyst system preferentially oxidizes the tetrahydroquinolines between two amino reactants, and the presence of TEMPO significantly enhances the capability of the first oxidation of THQs and makes it a kinetically controlled process, thus favoring the C-N bond-forming step. The developed chemistry features broad substrates, excellent functional tolerance, high chemo-selectivity, and no need for pre-preparation of specific aminating agents, which offers a practical way for diverse and atom-economic synthesis of 2-aminoquinolines that are difficult to prepare or inaccessible with the existing C-H amination approaches.

Copper-catalysed dehydrogenative α-C(sp3)–H amination of tetrahydroquinolines with O-benzoyl hydroxylamines

A copper-catalysed dehydrogenative α-C(sp³)–H amination of tetrahydroquinolines with O-benzoyl hydroxylamines has been demonstrated, which enables direct access to 2-alkylaminoquinolines in efficient manner.