Divergent synthesis of nitrogen heterocyclesviaH₂O-mediated hydride transfer reactions

Abstract

The H2O-promoted controllable synthesis of diverse 3-carboxyl and 3-acyl substituted tetrahydroquinolines and 3,4-dihydroquinolin-2(1H)-ones from readily available feedstocks was developed by a hydride transfer strategy.

Divergent synthesis of multi-substituted phenanthrenes via an internal redox reaction/ring expansion sequence

“…1 Because of its useful features such as transformation of the most inert C–H bond, C(sp 3 )–H bond, and no need of transition metal catalysts and external oxidants, many research groups have concentrated on this chemistry and various useful organic transformations have been developed (Scheme 1). 2–6…”

Synthesis of tetrahydroquinoline derivatives via electrochemical hydrocyanomethylation or hydrogenation of quinolines with MeCN

“…2 Therefore, efficient synthesis of THQs has attracted extensive attention and great progress has been made in the last few decades. 3 Among the synthetic methods of THQs that have been reported, the most classic one is the Pavorov reaction, which is the [4 + 2] cycloaddition of N -arylimines with electron-rich olefins. Hydrogenation of quinoline derivatives under transition-metal-catalysis conditions is another method that can provide a direct route to THQs.…”

Controllable Synthesis of N-Heterocycles via Hydride Transfer Strategy-Enabled Formal [5 + 1] and [5 + 2] Cyclizations

“…As a continuation of our interest in developing redox-neutral reactions for the rapid construction of pharmaceutically intriguing heterocyclic skeletons, herein we reported the formal [5 + 1] and [5 + 2] cyclizations via a hydride transfer strategy for controllable synthesis of indoline-fused tetrahydroquinolines and indole-fused benzazepines with indoles and N -alkyl o -aminobenzoketones as starting materials, respectively. It is worth mentioning that the Brønsted acids controlled selective [5 + 1] and [5 + 2] cyclizations with indoles via a hydride transfer strategy of unknown chemistry.…”

“…Hydride transfer/cyclization is characterized by the atom-economic and redox-neutral nature for C­(sp 3 )–H bond functionalization and generating heterocycles with a number of bonds breaking and forming in one operation. , Recently, a lot of organic synthons were applied to react with ortho -nitrogen/oxygen benzaldehyde B via hydride transfer-involved formal [5 + 1] cyclization reactions to generate six-membered heterocycles . Among the diverse nucleophiles, indole as a multifunctional nucleophile exhibited excellent reaction activity in these hydride transfer-involved transformations (Scheme a). − For example, in 2015, Sun and Xu’s group reported the p -TsOH·H 2 O-catalyzed [5 + 1] dearomatization reaction with 2-methylindole as a dinucleophile to react with 2-(pyrrolidin-1-yl)­benzaldehydes to provide 3,3′-spiroindolenines . Recently, our group developed a HFIP (1,1,1,3,3,3-hexafluoro-2-propanol)-mediated [5 + 1] dearomatization reaction between diverse indoles and 2-(pyrrolidin-1-yl)­benzaldehydes which made the transformation more convenient and suitable for more indoles .…”