Cu-Catalyzed Aerobic Oxidation of Di-tert-butyl Hydrazodicarboxylate to Di-tert-butyl Azodicarboxylate and Its Application on Dehydrogenation of 1,2,3,4-Tetrahydroquinolines under Mild Conditions

Abstract

A new class of co-catalytic system was developed with homogeneous CuI and di-tert-butyl azodicarboxylate for aerobic dehydrogenation of 1,2,3,4-tetrahydroquinolines under mild conditions. The developed co-catalytic system is consisting of di-tert-butyl azodicarboxylate-mediated dehydrogenation of 1,2,3,4-tetrahydroquinoline and aerobic oxidative regeneration of di-tert-butyl azodicarboxylate from di-tert-butyl hydrazodicarboxylate using molecular oxygen as a terminal oxidant. A variety of quinolines were efficiently synthesized by the developed Cu and di-tert-butyl azodicarboxylate co-catalytic system.

Organo‐Photoredox Catalyzed Oxidative Dehydrogenation of N‐Heterocycles

“…A limitation is that the reaction conditions were relatively forcing, for example, higher temperature (>100 °C), and the use of base and/or additives. Kim and co‐workers have reported the CuI/DBAD based dual catalytic system for the dehydrogenation of tetrahydroquinolines under aerobic conditions . Here, the first report of catalytic oxidative dehydrogenation of diverse N‐heterocycles by a visible‐light organo‐photoredox catalyst is reported.…”

Syntheses of 1H‐Indoles, Quinolines, and 6‐Membered Aromatic N‐Heterocycle‐Fused Scaffolds via Palladium(II)‐Catalyzed Aerobic Dehydrogenation under Alkoxide‐Free Conditions

“…[6] Both approaches represent ideal systems for the synthesis of the heteroarenes in terms of atom efficiency. In view of aerobic dehydrogenation, various catalytic systems with transition metals such as Ir, [7] Co, [8] Fe, [9] Cu, [10] Ru, [11] and Mn [12] have been developed. In particular, the Stahl group successfully employed heterogeneous cobalt oxide catalysts for the aerobic dehydrogenation of N-heterocycles, and ruthenium/quinone complexes for the similar dehydrogen- ation of tertiary indolines to indoles, respectively, in efficient manners.…”

Palladium Nanoparticles Stabilized by Metal–Carbon Covalent Bonds as an Expeditious Catalyst for the Oxidative Dehydrogenation of Nitrogen Heterocycles

“…Notably,t he first Cu-catalyzed dehydrogenation system was studied very recently,a nd it consistedo fh omogeneous CuI, di-tert-butyl azodicarboxylate (DBAD), and molecular oxygen (Scheme 1b). [11] Despite the great progress, most of these metal-catalyzed systems requireh arsh conditions, such as high temperatures and toxic organicsolvents, and show limited functional-groupt olerance. Considering the importance of quinoline and its derivatives as well as the current deficiency of methods for their preparation, it is still urgenta nd challenging to develop innovative catalytic de/hydrogenation transformations under mild and clean conditions with high efficiency.…”