Remote alkylation of N-(quinolin-8-yl)benzamides with alkyl bromides via ruthenium(ii)-catalyzed C–H bond activation

Palladium-Catalyzed Coordination-Induced Remote C-H Aryl Etherification/Amination of 8-Amidoquinolines

Herein, we report a direct method for palladium-catalyzed coordination-induced oxidative remote C-H aryl etherification of 8-amidoquinolines with p-benzoquinone monoacetal. The method provides access to C5-aryl etherified quinolines and shows site-selectivity different from that of typical palladium-catalyzed C(sp2)-H activation reactions. The p-benzoquinone monoacetals act both as oxidants and as aryl etherification reagents. By using proper substrates, C5-aminated quinolines and C4-etherifed 1-naphthylamine could also be formed.

α-Halocarbonyls as a Valuable Functionalized Tertiary Alkyl Source

This review introduces the synthetic organic chemical value of α-bromocarbonyl compounds with tertiary carbons. This α-bromocarbonyl compound with a tertiary carbon has been used primarily only as a radical initiator in atom transfer radical polymerization (ATRP) reactions. However, with the recent development of photo-radical reactions (around 2010), research on the use of α-bromocarbonyl compounds as tertiary alkyl radical precursors became popular (around 2012). As more examples were reported, α-bromocarbonyl compounds were studied not only as radicals but also for their applications in organometallic and ionic reactions. That is, α-bromocarbonyl compounds act as nucleophiles as well as electrophiles. The carbonyl group of α-bromocarbonyl compounds is also attractive because it allows the skeleton to be converted after the reaction, and it is being applied to total synthesis. In our survey until 2022, α-bromocarbonyl compounds can be used to perform a full range of reactions necessary for organic synthesis, including multi-component reactions, cross-coupling, substitution, cyclization, rearrangement, stereospecific reactions, asymmetric reactions. α-Bromocarbonyl compounds have created a new trend in tertiary alkylation, which until then had limited reaction patterns in organic synthesis. This review focuses on how α-bromocarbonyl compounds can be used in synthetic organic chemistry.

Copper-catalyzed selective C5-H bromination and difluoromethylation of 8-aminoquinoline amides using ethyl bromodifluoroacetate as the bifunctional reagent

A simple and effective method for the copper-catalyzed selective C5-H bromination and difluoromethylation of 8-aminoquinoline amides with ethyl bromodifluoroacetate as the bifunctional reagent was developed. The combination of cupric catalyst and alkaline additive results in a C5-bromination reaction, whereas cuprous catalyst combined with silver additive results in the C5-difluoromethylation reaction. This method has a broad substrate scope and allows for easy and convenient access to desired C5-functionalized quinolones with good to excellent yields.

Site-selective C5-H and N-H alkylation of unprotected 8-aminoquinolines

8-Aminoquinolines are the building blocks of many pharmaceutical compounds, which has motivated the scientific community to develop new ways to derivatize these compounds. In this work, we performed a site-selective C5-H and N-H alkylation of 8-aminoquinolines using para-quinone methides under extremely mild conditions. C5-H alkylation was performed using protecting group-free 8-aminoquinolines and in metal-free conditions. N-H alkylations were also carried out under mild conditions. All corresponding alkylation products were obtained in high to excellent yields.

Metal-free site-selective C-H cyanoalkylation of 8-aminoquinoline and aniline-derived amides with azobisisobutyronitrile

Using K₂S₂O₈, an efficient and metal-free site-selective C–H cyanoalkylation of 8-aminoquinoline and aniline-derived amides with AIBN (azobisisobutyronitrile) was developed. Without any catalyst, various substrates and functional groups were compatible to afford corresponding products in moderate to high yields. A mechanism study displayed that a radical–radical coupling process was involved via the N-centered radical generation and delocalization of aryl amides.

An efficient metal-free cyanoalkylation of 8-aminoquinoline and aniline-derived amides was achieved in the presence of K₂S₂O₈. The method showed good substrate tolerance and also suitable for bromination and dimerization reactions.

Three-component ruthenium-catalyzed remote C-H functionalization of 8-aminoquinoline amides

Multicomponent reactions can efficiently construct complex molecular structures from simple precursors. Herein, a novel ruthenium-catalyzed three-component highly selective remote C-H functionalization of 8-aminoquinoline amides has been described. The reaction tolerates a wide range of functional groups, producing arylation/difluoroalkylation products of olefins with potential biological activity and pharmaceutical value. Radical scavenging and radical clock experiments show that a free radical process is involved and a H/D exchange experiment suggests that the reaction might involve ortho-C-H activation of the aromatic ring. A possible mechanism is proposed.

Benchmark study of benzamide derivatives and four novel theoretically designed (L1, L2, L3, and L4) ligands and evaluation of their biological properties by DFT approaches

Four novel ligands, namely N-benzhydryl benzamide, N, N-diphenethyl benzamide, N, N-dihexyl benzamide, and N, N-dioctyl benzamide (L1, L2, L3, and L4, respectively), based on the benzamide unit were designed and computed for their different properties, such as absorption spectrum, dipole moment, theoretically expected biological properties, and frontier molecular orbitals, by evaluating the HOMO/LUMO energy orbitals strength with DFT approaches and comparing these properties with the R benzamide properties available in literature. All molecules have a suitable frontier molecular orbital diagram and L1 exhibits maximum absorption at 246.8 nm due to the strong electron donating effect of the diphenylmethane ligand group. Moreover, strongly extended conjugated groups caused a redshift in absorption spectra. Newly designed molecules may show strong biological activities against cancer, bacterial diseases, and harmful fungal disorders. Graphical abstract Orbital energy, electron density and frontier molecular orbitals view of four designed novel benzamide derivates.

Ruthenium-catalyzed remote C5-sulfonation of N-alkyl-8-aminoquinolines

Ruthenium-catalyzed remote C–H sulfonation of 8-aminoquinolines with single C5-selectivity.