A nickel catalyzed acceptorless dehydrogenative approach to quinolines

Abstract

A general, efficient and environmentally benign, one-step synthesis of substituted quinoline derivatives was achieved by acceptorless dehydrogenative coupling of o-aminobenzylalcohols with ketones and secondary alcohols catalyzed by a cheap, earth abundant and easy to prepare nickel catalyst [Ni(MeTAA)], featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)). A wide variety of substituted quinolines were synthesized in high yields starting from readily available o-aminobenzylalcohols and ketones or secondary alcohols. A few controlled reactions were carried out to establish the acceptorless dehydrogenative nature of the reactions.

NHC‐assisted Ni(II)‐catalyzed acceptorless dehydrogenation of amines and secondary alcohols

“…Based on the some reported studies, a possible mechanism for this catalytic system in the acceptorless dehydrogenation of benzyl amine and its derivatives is presented in Scheme . Initially, benzyl amine in the presence of a base is coordinated to Ni(L) to form the intermediate A .…”

“…In the case of the Ni‐catalyzed acceptorless dehydrogenation reactions, Dai and co‐workers developed three Ni (II) complexes with N'NN′ type pincer ligands for the dehydrogenation of primary alcohols to the carboxylic acids with the liberation of hydrogen gas . In addition, Parua and co‐workers reported the mono‐ and double‐dehydrogenative synthesis of quinolones derivatives starting from o ‐aminobenzylalcohols with ketones and secondary alcohols using [Ni (tetramethyltetraaza[14]annulene)] complex as active catalyst . Very recently, Liu et al .…”

Nickel‐Catalyzed Dehydrogenative Couplings

“…De Sarkar and Nanda independently reported an operationally simple procedure to prepare various polysubstituted quinolines from simple alcohol precursors (Scheme ). The acceptorless dehydrogenative process was efficiently carried out earth abundant Ni‐catalyst [Ni(MeTAA)].…”

Copper-catalyzed one-pot domino reactions via C–H bond activation: synthesis of 3-aroylquinolines from 2-aminobenzylalcohols and propiophenones under metal–organic framework catalysis

“…Quinolines have been recognized as valuable scaffolds commonly existing in numerous bioactive natural products and synthetic chemicals with versatile pharmacological and medicinal properties. [1][2][3][4] In particular, 3-acylquinolines have received remarkable interest as many of them are clinically used as drugs and pharmaceutical candidates. 5,6 Consequently, several strategies have recently been explored for the synthesis of these heterocycles.…”