2022/05/18 by Amit Kumar Guin, Rakesh Mondal, Gargi Chakraborty +2 · 32 citations
Chemical Engineering · Chemistry · #Alcohol oxidation #Asymmetric Hydrogenation and Catalysis #Carbon dioxide utilization in catalysis #Catalysis #Catalytic C–H Functionalization Methods #Chemistry #Combinatorial chemistry #Dehydrogenation #Diol #Ligand (biochemistry) #Medicinal chemistry #Organic chemistry #Phenanthroline #Pincer movement #Polymer chemistry #Redox #Ruthenium #Surface modification
paper · doi:10.1021/acs.joc.2c00311
published in The Journal of Organic Chemistry 87(11), 7106-7123 (American Chemical Society)
openalex publication_date 2022/05/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Herein, we report the synthesis and characterization of two ruthenium-based pincer-type catalysts, [ 1 ]X (X = Cl, PF 6 ) and 2, containing two different tridentate pincer ligands, 2-pyrazolyl-(1,10-phenanthroline) ( L 1 ) and 2-arylazo-(1,10-phenanthroline) ( L 2a/2b, L 2a = 2-(phenyldiazenyl)-1,10-phenanthroline; L 2b = 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline), and their application in the synthesis of substituted pyrroles via dehydrogenative alcohol functionalization reactions. In catalyst [ 1 ]X (X = Cl, PF 6 ), the tridentate scaffold 2-pyrazolyl-(1,10-phenanthroline) ( L 1 ) is apparently redox innocent, and all the redox events occur at the metal center, and the coordinated ligands remain as spectators. In contrast, in catalysts 2a and 2b, the coordinated azo-aromatic scaffolds are highly redox-active and known to participate actively during the dehydrogenation of alcohols. A comparison between the catalytic activities of these two catalysts was made, starting from the simple dehydrogenation of alcohols to further dehydrogenative functionalization of alcohols to various substituted pyrroles to understand the advantages/disadvantages of the metal–ligand cooperative approach. Various substituted pyrroles were prepared via dehydrogenative coupling of secondary alcohols and amino alcohols, and the N-substituted pyrroles were synthesized via dehydrogenative coupling of aromatic amines with cis -2-butene-1,4-diol and 2-butyne-1,4-diol, respectively. Several control reactions and spectroscopic experiments were performed to characterize the catalysts and establish the reaction mechanism.