abstract
A simple metal-ligand cooperative approach for the dehydrogenative functionalization of alcohols to various substituted quinolines and quinazolin-4(3H)-ones under relatively mild reaction conditions (<= 90 degrees C) is reported. Simple and easy-to-prepare air-stable Cu(II) complexes featuring redox-active azo-aromatic scaffolds, 2-arylazo-(1,10-phenanthroline) (L-1,L-2), are used as catalyst. A wide variety of substituted quinolines and quinazolin-4(3H)-ones were synthesized in moderate to good isolated yields via dehydrogenative coupling reactions of various inexpensive and easily available starting materials under aerobic conditions. A few control experiments and deuterium labeling studies were carried out to understand the mechanism of the dehydrogenative coupling reactions, which indicate that both copper and the coordinated azo-aromatic ligand participate in a cooperative manner during the catalytic cycle.
keywords
GAMMA-AMINO-ALCOHOLS; NON-INNOCENT LIGANDS; ONE-POT SYNTHESIS; OXIDATIVE SYNTHESIS; O-AMINOBENZAMIDES; RUTHENIUM; KETONES; CYCLIZATION; SECONDARY; QUINAZOLINONES
subject category
Chemistry
authors
Das, S; Sinha, S; Samanta, D; Mondal, R; Chakraborty, G; Brandao, P; Paul, ND
our authors
Paula Cristina Ferreira da Silva Brandão
Assistant Researcheracknowledgements
The research was supported by DST (Project: YSS/2015/001552). S.D. and G.C. acknowledge UGC, S.S. acknowledges IIESTS, and R.M. acknowledges CSIR for fellowship support. Financial assistance from IIESTS is acknowledged. P.B. acknowledges CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref UID/CTM/50011/2013), financial support by national funds through the FCT/MEC, and when appropriate additional financial support by FEDER under the PT2020 Partnership Agreement. The authors express their sincere gratitude to Dr. Asish Kr. Singha Deb, Scientific Officer, BARC, Trombay, Mumbai 400085, India, for performing the ICP-OES experiment.