Synthesis of Dibenzo[f,h]quinolines by Stepwise C–H Arylation of 2-Phenylpyridine and Reductive Cyclodehydrogenation

Abstract

A synthetic approach to dibenzo[f,h]quinolines and their derivatives is presented via stepwise ruthenium-catalyzed C-H arylation and potassium-mediated reductive cyclodehydrogenation from 2-phenylpyridine and aryl bromides. One dibenzo[f,h]quinoline derivative is used as a bidentate ligand to prepare a cyclometalated ruthenium complex. Two dibenzo[f,h]quinoline compounds and the ruthenium complex are characterized by single-crystal X-ray structural analysis.

LED-induced Ru-photoredox Pd-catalyzed C–H arylation of (6-phenylpyridin-2-yl)pyrimidines and heteroaryl counterparts

“…Pyridine is a frequently employed directing group, especially in cases of catalytic C–H arylation on adjacent phenyl rings ( Scheme 1A ), with a significant body of research on this topic having emerged over the last few years. Metal complex catalysts for C–H arylation of phenylpyridines are predominantly based on ruthenium, 5 rhodium 6 or palladium, 7 and to a lesser extent iron, 8 cobalt 9 or nickel. 10 Aryl donors have been diverse, including aryl halides, 5 o , p ,6 i benzoyl halides, 6 g aryl acylperoxides, 7 i arylboronic acids, 7 k Grignard reagents, 8 b triarylindium reagents, 6 a arylstannanes, 6 h arylsilanes, 5 e aryltrifluoroborate salts, 7 j diaryliodonium salts 7 f or alternative hypervalent iodine reagents 7 b and phenyldiazonium salts.…”