Synthesis of Quinoxaline 1,4-di-N-Oxide Analogues and Crystal Structure of 2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide

Yingjun Xu,Fanhong Wu,Minmin Zhang,Zhiyi Yao,Sheng Jiang

doi:10.3390/molecules16086894

Yingjun Xu, Fanhong Wu + Show 3 more

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https://doi.org/10.3390/molecules16086894

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Abstract

A series of quinoxaline 1,4-di-N-oxide analogues were prepared from benzofurazan N-oxide derivatives and β-diketone ester compounds by the improved Beirut reaction. The structures of the target products were characterized by NMR, MS, IR and elemental analysis measurements, and that of 2-carbomethoxy-3-hydroxyquinoxaline- di-N-oxide was further confirmed by single-crystal X-ray diffraction. Its crystal structure belongs to the monoclinic system, space group C2/c with a = 14.4320 (12) Å, b = 10.7514 (9) Å, c = 13.2728 (11) Å, V = 1958.5 (3) Å 3, Z = 8. The X-ray crystallographic analysis reveals that quinoxaline 1,4-di-N-oxide displays acyloin-endiol tautomerism.

Highlights

Some quinoxaline 1,4-di-N-oxides and their derivatives are useful materials that possess a wide range of antimicrobial activities and animal growth promotion effects [1,2,3,4]
Benzofurazan N-oxide derivatives can react with enamines [5], β-diketone esters [6], or any aldehyde or ketone containing two α-H [7,8] to form quinoxaline 1,4-di-N-oxides
When we first set out to discover novel and Molecules 2011, 16 biologically active compounds, we managed to synthesize a series of quinoxaline 1,4-di-N-oxide analogues with the NaH/THF reaction system, which offered shorter reaction times and gave higher yields

Summary

Introduction

Some quinoxaline 1,4-di-N-oxides and their derivatives are useful materials that possess a wide range of antimicrobial activities and animal growth promotion effects [1,2,3,4]. Benzofurazan N-oxide derivatives can react with enamines [5], β-diketone esters [6], or any aldehyde or ketone containing two α-H [7,8] to form quinoxaline 1,4-di-N-oxides. This reaction, which has been referred to as the Beirut reaction, is an excellent method for preparing these heterocyclic compounds. When we first set out to discover novel and Molecules 2011, 16 biologically active compounds, we managed to synthesize a series of quinoxaline 1,4-di-N-oxide analogues with the NaH/THF reaction system, which offered shorter reaction times and gave higher yields

Results and Discussion

General

Crystal structure determination

Conclusions