Herein, we report a simple, phosphine-free, and inexpensive catalytic system based on a manganese­(II) complex for synthesizing different important N-heterocycles such as quinolines, pyrroles, and pyridines from amino alcohols and ketones. Several control experiments, kinetic studies, and DFT calculations were carried out to support the plausible reaction mechanism. We also detected two potential intermediates in the catalytic cycle using ESI-MS analysis. Based on these studies, a metal–ligand cooperative mechanism was proposed.

A new family of phosphine free organometallic ruthenium(II) catalysts (Ru1–Ru4) supported by bidentate NN Schiff base ligands (L1–L4 where L1=N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazineylidene)methyl) aniline, L2=N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazineylidene)methyl)aniline, L3=N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazineylidene)methyl)‐ aniline and L4=N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazineylidene)methyl) aniline) was prepared and characterized. These half‐sandwich complexes acted as catalysts for C−C bond formation and exhibited excellent performance in the dehydrogenative coupling of ketones and amides. In the synthesis of C–C bonds, alcohols were utilized as the alkylating agent. A broad range of substrates, including sterically hindered ketones and alcohols, were well tolerated under the optimized conditions (TON up to 47000 and TOF up to 11750 h−1). This ruthenium (II) catalysts were also active towards the dehydrogenative cyclization of o‐amino benzyl alcohol for the formation of quinolines derivatives. Various polysubstituted quinolines were synthesized in moderate to excellent yields (TON up to 71000 and TOF up to 11830 h−1). Control experiments were carried out and the ruthenium hydride intermediate was characterized to support the reaction mechanism and a probable reaction pathway of dehydrogenative coupling for the C−C bond formation has been proposed.

Base-metal catalysts Co1, Co2 and Co3 were synthesized from designed pincer ligands L1, L2 and L3 having NNN donor atoms respectively. Co1, Co2 and Co3 were characterized by IR, UV–Vis....

Salen-type base-metal copper(II) complexes derived from unsymmetrical Schiff ligands were designed and synthesized by ligands L1H to L4H in moderate yields. Synthesized unsymmetrical ligands L1H to L4H and corresponding copper...

A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2‐((2‐(4‐methoxybenzylidene)‐1‐phenylhydrazinyl)methyl)pyridine, L2H = N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono)methyl)aniline, L3H = N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono)methyl) aniline and L4H = 4‐(4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X‐ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre‐catalyst for the gram‐scale synthesis of octinoxate, which is utilized as a UV‐B sunscreen agent.