Synthesis of quinoline derivatives from anilines and aldehydes catalyzed by Cp 2 ZrCl 2 and recyclable Cp 2 ZrCl 2 /MCM-41 system

Reactivity of Woollins' Reagent toward 2‐En‐1‐imines (Schiff Bases): A Facile Approach to Synthesize New Selenium‐Phosphorus‐Nitrogen Heterocycles

“…Schiff bases can be prepared from aliphatic or aromatic amines and carbonyl‐containing compounds by nucleophilic addition, following by a dehydration to give imines. In this study, we particularly focused on conjugated Schiff bases, thus a series of conjugated Schiff bases (2‐en‐1‐imines) 1a – n was synthesized by means of literature procedures . First, we investigated the reaction of typical simple Schiff bases with Woollins' Reagent.…”

A Novel Gemini Sulfonic Ionic Liquid Immobilized MCM‐41 as Efficient Catalyst for Doebner‐Von Miller Reaction to Quinoline

“…This is possibly due that the decreasing intensity of XRD peak over IL-supported MCM-41 is attributed to the adsorption influence to the X-ray by the layer of ionic liquid supported on the outside and inner surface of MCM-41. [41] In addition, the diffraction peak of (100) shift slightly toward higher 2θ over the IL-supported MCM-41 samples, compared to the parent MCM-41 one. This may be resulted from the decreasing mesopore size over IL-supported MCM-41 samples, according to the rule of Bragg (λ = 2d.sinθ).…”

Optimizing the Iodide/Iodonium/O2 Oxidation Cycle Enhances the Scope, Selectivity, and Yields of Hydroiodic Acid‐Catalyzed Multicomponent Cyclocondensation Reactions

“…and further developed by others [31,33,38–41] . When adapting the reported procedure to the synthesis of alkyl‐tethered “multicore” benzoquinoline synthesis, [5,42–45] we encountered low yields and significant secondary amine formation from competitive reduction of the imine intermediate. These issues prompted us to investigate the generation and relevancy of the relevant oxidant(s) and define the mechanism of the oxidative catalytic cycle in sufficient detail to optimize yields and broaden the scope of the Wang‐Kozlov MCR.…”

“…The concentration of oxygen in air alone is insufficient to prevent the iminium cation from accepting hydride from the dihydroquinoline intermediate, irreversibly giving the secondary amine (Scheme 1). This oft‐reported shunt [42,44,45,47] potentially limits the theoretical yield of quinoline to 50% under the most extreme oxidant deficiency. Replacing air with oxygen in part addresses this inefficiency, as evidenced by the higher yield of quinoline coupled with a diminished fraction of the secondary amine 3 ( cf ., entries 1, 2).…”