An efficient reductive cyclization of o-nitrobenzyl ketone compounds was achieved by using a Hantzsch 1,4-dihydropyridine ester as a biomimetic reducing agent in the presence of catalytic palladium on carbon. 2-Substituted indoles were obtained in good yields. Investigation of the mechanism suggests that palladium hydride promotes the reduction of nitro group, and acetic acid was beneficial for the loss of water to produce the intended product. This reaction system can not only broaden the use of Hantzsch 1,4-dihydropyridine ester, but it also provides a novel approach for preparing indole compounds.
An efficient reductive cyclization of o-nitrobenzyl ketone compounds was achieved by using a Hantzsch 1,4-dihydropyridine ester as a biomimetic reducing agent in the presence of catalytic palladium on carbon. 2-Substituted indoles were obtained in good yields. Investigation of the mechanism suggests that palladium hydride promotes the reduction of nitro group, and acetic acid was beneficial for the loss of water to produce the intended product. This reaction system can not only broaden the use of Hantzsch 1,4-dihydropyridine ester, but it also provides a novel approach for preparing indole compounds.
Palladium and copper catalyzed one-pot Sonogashira reaction of 2-nitroiodobenzenes with aryl acetylenes and subsequent regioselective hydration in water: synthesis of 2-(2-nitrophenyl)-1-aryl ethanones
作者:Sabir Ahammed、Raju Dey、Brindaban C. Ranu
DOI:10.1016/j.tetlet.2013.05.021
日期:2013.7
An attempted Sonogashira reaction of 2-nitroiodobenzene and phenyl acetylene catalyzed by Pd(PPh3)(4)/Cu in water in the presence of pyrrolidine proceeds with simultaneous regioselective hydration of the Sonogashira alkyne leading to the corresponding aryl ketone. A series of functionalized 2-(2-nitrophenyl)-1-aryl ethanones are obtained in high yields by this procedure. (C) 2013 Elsevier Ltd. All rights reserved.