ACCESSIBILITY OF ZWITTERIONIC COMPOUNDS FROM PRIMARY AMINES AND 2,5-DIHYDROXY-1,4-BENZOQUINONE

Farba Bouyagui Tamboura,Papa Samba Camara,Modou Lo,Issa Samb,Mohamed Gaye,Abdi Ould Kaihil

doi:10.17628/ecb.2019.8.193-202

Farba Bouyagui Tamboura, Papa Samba Camara + Show 4 more

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https://doi.org/10.17628/ecb.2019.8.193-202

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Abstract

Following the discovery of an unprecedented transamination reaction between primary alkylamines and a quinonoid molecule of the type C 6 H 2 (NHCH 2 R) 2 (=O)2 (I), obtained from commercially available diaminoresorcinol.2HCl, we have extended this method to the use of primary arylamines and found that, in contrast, secondary amines led to a different outcome. Whereas functionalized molecules of type I , which are best described as 6π +6π zwitterions, were obtained with aniline or 4-methoxyaniline, no transamination was observed with tBuNH 2 in ethanol. However, a reaction which afforded salt 2-methylpropan-2-aminium 4-(methylamino)-3,6-dioxocyclohexa-1,4-dien-1-olate ( 2b) took place in water and resulted from hydrolysis of the imine group and deprotonation of 5-hydroxy-2-(methylamino)-4-(methylimino)-cyclohexa-2,5-dienone ( 1a) . Under similar conditions, secondary amines led to comparable results. The cations associated with the anionic quinonoid are readily exchanged in the presence of a primary amine. Whereas for the transamination reaction, basic amines react under mild conditions, slightly harsher conditions are needed for less basic amines such as piperidine, diisopropylamine, or diethylamine. Transamination reactions were also performed with 5-hydroxy-2-(methylamino)-4-(methylimino)-cyclohexa-2,5-dienone ( 1a) , which is more soluble in organic solvents than 2-amino-5-hydroxy-4-iminocyclohexa-2,5-dienone (compound I ) This led to the first examples of quinonoidal zwitterions functionalized with different alkyl groups on the nitrogen atoms. A number of compounds were characterized by X-ray diffraction, which allowed a better understanding of their electronic situation, and in many cases, the presence of multiple hydrogen-bond donors and acceptors results in crystal packings dominated by these interactions.

Highlights

Following the discovery of an unprecedented transamination reaction between primary alkylamines and a quinonoid molecule of the type C6H2(NHCH2R)2(=O)2 (I), obtained from commercially available diaminoresorcinol.2HCl, we have extended this method to the use of primary arylamines and found that, in contrast, secondary amines led to a different outcome
Benzoquinonemonoimines were obtained by transamination reaction of alkyl and arylamines with specific reactants like diaminoresorcinol dihydrochloride or by esterification reaction followed by reduction
The aim of this paper is to show that transdialkylaminobenzoquinone and diarylaminobenzoquinones can be obtained with 2,5-dihydroxybenzoquinone at high temperature

Summary

Introduction

Organic compounds containing a quinonoid fragment are of great interest because of their intrinsic properties and their numerous applications in chemistry, physical chemistry and biology. In particular, benzoquinonemonoimines have been found to display unique properties in various areas such as coloring, organic, supramolecular, coordination, organometallic chemistry and homogeneous catalysis. Previous studies have shown that the reactions between alkylamines or arylamines and benzoquinone gave a trans-dialkylaminobenzoquinone or trans-diarylamino-benzoquinone and monoarylamino products. Similar reactions with 2,5dihydroxybenzoquinone have been achieved yielding transdialkylaminobenzoquinone and diarylaminobenzoquinone products whose nickel complexes are very active in catalysis. Benzoquinonemonoimines were obtained by transamination reaction of alkyl and arylamines with specific reactants like diaminoresorcinol dihydrochloride or by esterification reaction followed by reduction. The aim of this paper is to show that transdialkylaminobenzoquinone and diarylaminobenzoquinones can be obtained with 2,5-dihydroxybenzoquinone at high temperature. Organic compounds containing a quinonoid fragment are of great interest because of their intrinsic properties and their numerous applications in chemistry, physical chemistry and biology.. Benzoquinonemonoimines have been found to display unique properties in various areas such as coloring, organic, supramolecular, coordination, organometallic chemistry and homogeneous catalysis.. Previous studies have shown that the reactions between alkylamines or arylamines and benzoquinone gave a trans-dialkylaminobenzoquinone or trans-diarylamino-benzoquinone and monoarylamino products.. Similar reactions with 2,5dihydroxybenzoquinone have been achieved yielding transdialkylaminobenzoquinone and diarylaminobenzoquinone products whose nickel complexes are very active in catalysis.. Benzoquinonemonoimines were obtained by transamination reaction of alkyl and arylamines with specific reactants like diaminoresorcinol dihydrochloride or by esterification reaction followed by reduction.. The aim of this paper is to show that transdialkylaminobenzoquinone and diarylaminobenzoquinones can be obtained with 2,5-dihydroxybenzoquinone at high temperature. A zwitterion 6π + 6 π electrons (I) and a precursor of zwitterion 12π electrons (2,5-dihydroxy benzoquinone) (II)

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