Efficient synthesis of pyrrolo[1,2-a]quinoxalines catalyzed by a Brønsted acid through cleavage of C–C bonds

Abstract

An efficient and convenient one-pot domino reaction for the direct synthesis of pyrrolo[1,2-a]quinoxalines has been developed. This approach utilizes an imine formation reaction, SEAr reaction and cleavage of C-C bonds catalyzed by a Brønsted acid. β-Diketones and β-keto esters are both well tolerated to give the corresponding products in moderate to excellent yields.

Copper‐Catalyzed One‐Pot Synthesis of Pyrrolo[1,2‐a]quinoxaline Derivatives from 1‐(2‐Aminophenyl)‐pyrroles and Aldehydes

“…All the synthesized pyrrolo[1,2‐ a ]quinoxaline derivatives ( 3 a‐t ) could be characterized by spectral data ( 1 H NMR, 13 C NMR, and Mass) are in full agreement with the proposed structures. The spectroscopic and analytical data of reported compounds were in good agreement with those in the literature . To further explore the efficiency and practicality of this reaction, the gram‐scale reaction (10.0 mmol) was performed with these reaction conditions (Scheme ).…”

“…In 2015, Zhai and co‐workers explored the I 2 ‐catalyzed aerobic oxidative process for the synthesis of pyrrolo[1,2‐ a ]quinoxalines by using benzylamines and 1‐(2‐aminophenyl)pyrroles in o ‐xylene as the solvent at 140 °C (Scheme b) . Recently, Ma and co‐workers also reported a facile and efficient strategy for the direct synthesis of pyrrolo[1,2‐ a ]quinoxalines from 1‐(2‐aminophenyl)pyrroles and β‐diketones or β‐keto esters using TsOH.H 2 O as a catalyst in DMSO as the solvent at 120 °C (Scheme c) . In addition, Kamal et al.…”

Tin(ii) chloride dihydrate/choline chloride deep eutectic solvent: redox properties in the fast synthesis of N-arylacetamides and indolo(pyrrolo)[1,2-a]quinoxalines

“…Thus, synthetic equivalents with several combinations of atoms might be used. On the other hand, a more convenient strategy based on pyrrole or indole derivatives can be developed for the formation of the pyrazine ring; 36 and for this 1-(2-aminophenyl)pyrrole/indole has been widely used as starting material in combination with a broad scope of substrates including aldehydes, 37-40 alcohols, 41 ketones, 42,43 a-aminoacids, 44 carboxylic acids, 45 2-methylpyridine/quinoline 46 and benzylamines 47 (Scheme 1). Analogously, other synthetic approaches have employed arylhalides, 48 arylisocyanides, 49 and nitrobenzene 24 having ortho-substituted pyrrole or indole rings (Scheme 1).…”

Iron Catalyzed Cascade Protocol for the Synthesis of Pyrrolo[1, 2‐a]quinoxalines: A Powerful Tool to Access Solid State Emissive Organic Luminophores

“…reported the synthesis of indolo‐ and pyrrolo[1, 2‐ a ]quinoxalines by using a stoichiometric quantity of iodine, Zhai and co‐workers reported use of iodine as a catalyst and oxygen as an oxidant while Nath et al . as well as Chen et al . discovered Brønsted acid for the same.…”