Domino Oxidative Cyclization for the One‐Pot Synthesis of Pyrrolo[1, 2‐a]quinoxaline Derivatives

Abstract

An oxidative cyclization of 1‐(2‐aminophenyl)pyrrole with styrenes has been developed for the synthesis of pyrrolo[1, 2‐a]quinoxaline derivatives using I2/2‐iodoxybenzoic acid (IBX) in DMSO as an effective oxidant. I2 is found to catalyze effectively the oxidative cyclization of phenylacetylene and ethyl benzoylacetate with 1‐(2‐aminophenyl)pyrrole even in the absence of IBX to generate pyrrolo[1, 2‐a]quinoxaline derivatives under metal‐free conditions.

Efficient synthesis of pyrrolo[1,2-α]quinoxalines mediated by ethyl 2-(4-nitrophenyl)azocarboxylate

“…When phenylglyoxal monohydrate was examined, the corresponding 4-benzoyl pyrrolo[1,2-α]quinoxaline was produced in an excellent yield ( 51 ). 19 a ,31 It is particularly noteworthy that both formalin and paraformaldehyde could be utilized as one-carbon synthons in our developed method ( 52 ). Compared to the previous one-carbon synthons such as DMF, DMSO, and PEG-400 in this transformation, 22,32 our method provides more practical and atom-efficient routes for the pyrrolo[1,2-α]quinoxaline core.…”

A Golden Synthetic Approach to 2-(1H-Pyrrol-1-yl)anilines and Pyrrolo[1,2-a]quinoxalines through a Gold Carbene Intermediate

“…13 C-NMR (CDCl3, 100 MHz): δ 164. 7,143.5,136.9,133.7,131.8,130.5,130.4,129.9,129.6,129.5,127.5,127.2,123.1,118.3,115.7,113.7,109.2,59.6,14.3,12.1. HRMS Anal.Calcd.…”

“…Some publications indicated the use of transition metals, and others discussed metal-free reaction conditions (Scheme 1, reaction a). [4][5][6][7][8][9][10] According to the literature, the same procedures utilized in synthesizing 5x limit the pyrrole ring derivatization. Thus, new approaches for determining distinct functional groups in the 5y and quinoxaline skeletons could significantly contribute to the literature.…”

Recent advances in the transition-metal-free synthesis of quinoxalines

“…In 2018, Reddy et al demonstrated a highly efficient metal-free one-pot domino oxidative cyclization approach for the construction of several pyrrolo[1,2- a ]quinoxaline derivatives from alkenes and alkynes ( Scheme 30 ). 103 With the help of I 2 as the catalyst and 2-iodoxybenzoic acid (IBX) as the oxidant, the treatment of alkenes 59 with 2-(1 H -pyrrol-1-yl)aniline 90 was found to take place in DMSO to deliver the desired products 91 in good yield. A variety of electron-donating and electron-withdrawing substituents present on the aryl ring of alkenes smoothly participated in this reaction.…”