Radical Cation Salt-Promoted Catalytic Aerobic sp3 C–H Oxidation: Construction of Quinoline-Fused Lactones and Lactams

Oxidative Tandem Cyclization of Glycine Esters with Propargyl Alcohols

A facile and efficient aerobic oxidative (4 + 2)-cyclization/aromatization/lactonization tandem reaction of N-aryl glycine esters with propargyl alcohols to access quinoline-fused lactones is reported. The reaction can be extended to homopropargylic alcohols too. The transformation is straightforward to perform under mild conditions and scalable, and both reaction components are readily available.

The Intramolecular Povarov Tool in the Construction of Fused Nitrogen-Containing Heterocycles

Nitrogen heterocycles are part of the structure of natural products and agents with important biological activity, such as antiviral, antibiotic, and antitumor drugs. For this reason, heterocyclic compounds are one of today's most desirable synthetic targets and the Povarov reaction is a powerful synthetic tool for the construction of highly functionalized heterocyclic systems. This process involves an aromatic amine, a carbonyl compound, and an olefin or acetylene to give rise to the formation of a nitrogen-containing heterocycle. This review illustrates advances in the synthetic aspects of the intramolecular Povarov reaction for the construction of intricate nitrogen-containing polyheterocyclic compounds. This original review presents research done in this field, with references to important works by internationally relevant research groups on this current topic, covering the literature from 1992 to 2022. The intramolecular Povarov reactions are described here according to the key processes involved, using different combinations of aromatic or heteroaromatic amines, and aliphatic, aromatic, or heteroaromatic aldehydes. Some catalytic reactions promoted by transition metals are detailed, as well as the oxidative Povarov reaction and some asymmetric intramolecular Povarov processes.

Photocatalytic Synthesis of Quinolines via Povarov Reaction under Oxidant-Free Conditions

We describe here an approach for synthesizing quinolines either from N-alkyl anilines or from anilines and aldehydes. A dual-catalyst system consisting of a photocatalyst and a proton reduction cocatalyst is employed. Without the use of any sacrificial oxidant and under extremely mild conditions, the reactions afford quinolines in excellent yields and produce H₂ as a byproduct.

C-centered radical-initiated cyclization by directed C(sp3)–H oxidative functionalization

C(sp3)–H functionalization is attracting constant attention. This review emphasizes C-centered radicals initiated cyclization strategies by directed C(sp3)–H oxidative functionalization since 2012.

Visible-light-induced and copper-catalyzed oxidative cyclization of substituted o-aminophenylacetylene for the synthesis of quinoline and indole derivatives

A visible-light-induced and copper-catalyzed oxidative cyclization of substituted o-aminophenylacetylene for the synthesis of quinoline and indole derivatives was developed.

One-electron oxidative dehydrogenative annulation and cyclization reactions

This review focuses on the recent advances in one-electron oxidation involved oxidative dehydrogenative annulations and cyclizations for the intermolecular and intramolecular construction of valuable ring structures.

Oxidative [4+2] Cycloaddition of α-(N-Arylamino) Carbonyls with Aryl Alkenes by Multiple C-H Functionalizations and [1,2]-Aryl Shifts

A new, general copper-catalyzed oxidative tandem [4+2] cycloaddition of α-(N-arylamino) carbonyl compounds with aryl alkenes to produce highly substituted quinolines has been developed, which allows the formation of three new C-C bonds through a sequence of multiple C-H functionalizations, annulation, and [1,2]-aryl shifts.

Oxone promoted dehydrogenative Povarov cyclization of N-aryl glycine derivatives: an approach towards quinoline fused lactones and lactams

Oxone promoted intramolecular dehydrogenative imino Diels–Alder reaction (Povarov cyclization) of alkyne tethered N-aryl glycine esters and amides has been explored, thus affording biologically significant quinoline fused lactones and lactams.

Radical Cation Salt-initiated Aerobic C-H Phosphorylation of N-Benzylanilines: Synthesis of α-Aminophosphonates

A radical cation salt-initiated phosphorylation of N-benzylanilines was realized through an aerobic oxidation of the sp3 C-H bond, providing a series of α-aminophosphonates in high yields. An investigation of the reaction scope revealed that this mild catalyst system is superior in good functional group tolerance and high reaction efficiency. The mechanistic study implied that the cleavage of the sp3 C-H bond was involved in the rate-determining step.

Metal-free photocatalyzed aerobic oxidative Csp3–H functionalization of glycine derivatives: one-step generation of quinoline-fused lactones

This reaction provides facile access to a series of valuable quinoline-fused lactones at room temperature under an air atmosphere.

Facile Construction of Quinoline-2-carboxylate Esters through Aerobic Oxidation of Alkyl 4-Anilinocrotonates Induced by a Radical Cation Salt

A facile construction of quinoline-2-carboxylate esters through an aerobic oxidation of alkyl 4-anilinocrotonates is described. In the presence of dioxygen, sp³ C-H bonds in 4-anilinocrotonates can easily be oxidized by using a catalytic amount of a radical cation salt, providing a radical intermediate. After further oxidation and domino cyclization, the desired quinoline derivatives were afforded in high yields. This reaction provides a new way to construct the pharmaceutically relevant quinoline skeleton, avoiding harsh reaction conditions and tedious starting material synthesis.

A dual removable activating group enabled the Povarov reaction of N-arylalanine esters: synthesis of quinoline-4-carboxylate esters

A dual removable activating group enabled Povarov reaction of N-arylalanine esters was reported.

Recent progress in mild Csp3–H bond dehydrogenative or (mono-) oxidative functionalization

This review summarizes recent advances in mild and green dehydrogenative and mono-oxidative Csp³–H bond functionalization reactions, considering both new approaches and the re-elaboration of known methodologies.

Direct C–H heteroarylation of azoles with 1,2-di(pyrimidin-2-yl)disulfides through C–S cleavage of disulfides

C–C bond construction via C–H bond functionalization of oxazoles/thiazoles and C–S bond cleavage of di(hetero)aryl disulfides are described.

TBHP mediated oxidation of N-2-alkynylphenyl α-amino carbonyl compounds to oxalic amides using visible light photoredox catalysis and their application in the synthesis of 2-aryl indoles

Visible light promoted the oxidation of compounds 1 to amides 2 which were easily transferred to compounds 12.