Dinuclear Ru(II) Schiff Base Complex Catalyzed One-Pot Synthesis of Quinolines through Acceptorless Dehydrogenative Coupling of Secondary Alcohols with 2-Nitrobenzyl Alcohol
Gopal Deshmukh, Santosh J. Gharpure and Ramaswamy Murugavel*,
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引用次数: 0
Abstract
Dinuclear Ru(II) complexes [(p-cymene)2(RuCl)2L1]2X (X = BF4 (Ru1); X = PF6 (Ru2)) and mononuclear [(p-cymene)(RuCl)L2]BF4 (Ru3) (where L1 = N,N′-(3,3′,5,5′-tetraisopropyl-[1,1′-biphenyl]-4,4′-diyl)bis(1-(pyridin-2-yl)methanimine); L2 = N-(2,6-diisopropyl-phenyl)-1-(pyridin-2-yl)-methanimine) have been synthesized and characterized by spectroscopic and analytical techniques. Dinuclear Ru1 and Ru2 orchestrate direct transformation of 2-nitrobenzyl alcohols to quinolines under mild conditions with significant efficiency even when employed at a minimal catalyst loading of 0.1 mol %. Proportional experiments carried out with the corresponding mononuclear complex Ru3 by keeping the Ru content the same (0.2 mol % of Ru3) reveal superior activity by the bimetallic system Ru1 for the one-pot quinoline synthesis. Late-stage functionalization of bioactive steroids and scale-up synthesis demonstrate the practical applicability of the present catalyst system. A probable mechanism of this conversion is proposed based on trapping of many of the intermediates by ESI-mass spectroscopy. These mechanistic studies have further been substantiated by ReactIR studies by monitoring the progress of the reaction in real time.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.