Visible-Light-Mediated Synthesis of α-Aryl Ester Derivatives via an EDA Complex

We report an efficient radical-based and photocatalyst-free method for the C(sp2)-C(sp3) cross-coupling reaction to synthesize α-aryl ester derivatives. The process starts from a β-keto ester and an electron-deficient halogenated aryl halide under alkaline conditions to form an electron donor-acceptor complex and is driven by visible light. From the synthetic point of view, this newly established method represents a simple way to access arylpropionic acids from commercially available and cheap starting materials.

Copper-catalyzed three-component annulation toward pyrroles via the cleavage of two C-C bonds in 1,3-dicarbonyls

The first copper-catalyzed three-component annulation of α,β-unsaturated ketoximes, 1,3-dicarbonyls and paraformaldehyde has been documented. This novel strategy achieved the two C-C bond cleavage of 1,3-dicarbonyl compounds directly as a single-carbon synthon and provided a new and highly efficient method for the synthesis of 2,3-disubstituted pyrroles in moderate to good yields with broad functional group compatibility.

Growth vector elaboration of fragments: regioselective functionalization of 5-hydroxy-6-azaindazole and 3-hydroxy-2,6-naphtyridine

This article discusses the reactivity of an 6-azaindazole (1) and a 2,6-naphthyridine (2), proposed to be “heteroaromatic rings of the future” which would be useful for fragment-based drug discovery (FBDD)...

Copper-Catalyzed Ullmann-Type Coupling and Decarboxylation Cascade of Arylhalides with Malonates to Access α-Aryl Esters

We have developed a high-efficiency and practical Cu-catalyzed cross-coupling to directly construct versatile α-aryl-esters by utilizing readily available aryl bromides (or chlorides) and malonates. These gram-scale approaches occur with turnovers of up to 1560 and are smoothly conducted by the usage of a low catalyst loading, a new available ligand, and a green solvent. A variety of functional groups are tolerated, and the application occurs with α-aryl-esters to access nonsteroidal anti-inflammatory drugs (NSAIDs) on the gram scale.

Transition metal-catalyzed arylation of unstrained C-C single bonds

Carbon-carbon bond activation is one of the most challenging and important research areas in organic chemistry. Selective C-C bond activation of unstrained substrates is difficult to achieve owing to its inert nature and competitive side reactions, but the ubiquitous presence of C-C bonds in organic molecules makes this transformation attractive and of vital importance. Moreover, transition metal-catalyzed arylation of unstrained C-C single bonds can realize the cleavage of old C-C bonds and introduce important aryl groups into the carbon chain to construct new C-C bonds at the same time, providing a powerful and straightforward method to reconstruct the skeleton of the molecules. In recent years, considerable progress has been made in the area of direct arylation of C-C bonds, and β-C elimination or oxidative addition strategies play key roles in these transformations. This review summarizes recent achievements of transition metal-catalyzed arylation of unstrained C-C bonds, demonstrated by various kinds of substrates including alcohol, nitrile and carbonyl compounds, and each example is detailed by its corresponding mechanism, catalytic system and scope of the substrate.

An efficient synthesis of 6-arylbenzo[4,5]imidazo[2,1-a]isoquinolines via sequential α-arylation of carbonyl and deacylation catalyzed by CuI

Dibenzoyl methane was found to undergo α-arylation of carbonyl and deacylation reaction with 2-(2-bromophenyl)-1H-benzo[d]imidazoles catalyzed by CuI in the presence of Cs₂CO₃, and provided an efficient synthesis of 6-arylbenzo[4,5]imidazo[2,1-a]isoquinolines.

Selective Oxidative Decarbonylative Cleavage of Unstrained C(sp(3))-C(sp(2)) Bond: Synthesis of Substituted Benzoxazinones

A transition metal (TM)-free practical synthesis of biologically relevant benzoxazinones has been established via a selective oxidative decarbonylative cleavage of an unstrained C(sp(3))-C(sp(2)) bond employing iodine, sodium bicarbonate, and (t)butyl hydroperoxide in DMSO at 95 °C. Control experiments and Density Functional Theory (DFT) calculations suggest that the reaction involves a [1,5]H shift and extrusion of CO gas as the key steps. The extrusion of CO has also been established using PMA-PdCl2.

Copper-catalyzed direct α-ketoesterification of propiophenones with acetophenones via C(sp3)–H oxidative cross-coupling

A Cu-catalyzed direct α-ketoesterification of propiophenones with acetophenones via C(sp³)–H oxidative cross-coupling was developed by using O₂ as an oxidant.