ChemInform Abstract: A Convenient Procedure for the Oxidative Dehydrogenation of N‐Heterocycles Catalyzed by FeCl₂/DMSO.

Progress in the Chemistry of Tetrahydroquinolines

“…Dehydrogenation of Tetrahydroquinolines 1,2,3,4-THQs have been aromatized into the corresponding quinoline derivatives using a large number of catalysts, including metal catalysts and organocatalysts (Scheme 435). Some catalysts employed for this purpose include photoredox Ru catalyst 1607 and cobalt catalyst 1609 in the presence of visiblelight, 653 [Ru(phd) 3 ](PF 6 ) 2 1608 and Co(salophen) 1610, 654 Ru(II)-NHC complexes 1611, 655 palladium nanoparticles/ TBHP, 656,657 Pt/C, 535 cobalt oxide supported on nitrogendoped carbon, 658 cobalt porphyrin, 659 FeCl 2 /DMSO, 660 iron− nitrogen-doped graphene, 661 CuI and di-tert-butyl azodicarboxylate (DABD), 662 Rose Bengal/visible light, 663 graphite particles and DC high voltage (HV) in air, 664 and TEMPO as an organoelectrocatalyst. 665 Zhang and co-workers developed a copper-catalyzed dehydrogenative α-C(sp 3 )−H amination of tetrahydroquinolines 1612 at their C-2 position with O-benzoyl hydroxyl-amines1613 in the presence of butylated hydroxytoluene (BHT), Cu(I) iodide, and a 1:1 KOH/K 2 CO 3 mixture, and that afforded the C-2 amino-functionalized quinoline derivatives 1614 (Scheme 436).…”