Ecofriendly syntheses of phenothiazones and related structures facilitated by laccase – a comparative study

Cannatelli, Mark D.; Ragauskas, Arthur J.

doi:10.1016/j.tetlet.2016.07.016

Cited by 13 publications

(17 citation statements)

References 51 publications

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“…Phenothiazines are heterocyclic sulphur compounds applicable in many areas of medicine, in particular in the treatment of neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases [ 74 ]. Considering that laccases can oxidize hydroquinones and catechols to produce in situ p - and o -quinones, the cross-coupling reactions involving sulphur-based nucleophiles (1,2-ethanedithiol or 2-aminothiophenol) were exploited providing a sustainable approach for the synthesis of 2,3-ethylenedithio1,4-quinone and phenothiazine substructures ( Scheme 16 A) [ 97 , 109 ].…”

Section: Application Of Laccases In Bio-oxidative Synthesis Of Heterocyclic Compoundsmentioning

confidence: 99%

“…The coupling between 1,4-quinones and 2-aminothiophenol mediated by the T. villosa laccase, yielded the correspondent phenothiazine derivatives at 24–61% yields ( Scheme 16 A) providing a sustainable approach for the synthesis of this biologically important class of compounds. However, relatively low yields were obtained (9–53%) when the reaction started from the hydroquinones, due to the competitive reaction of dimerization of 2-aminothiophenol [ 97 ].…”

Section: Application Of Laccases In Bio-oxidative Synthesis Of Heterocyclic Compoundsmentioning

confidence: 99%

“… ( A ) Laccase-catalysed coupling reactions of 1,2-ethanedithiol or 2-aminothiophenol with 1,4-quinones; ( B ) Proposed reaction mechanism for the laccase-facilitated synthesis of phenothiazine derivatives [ 97 ]; ( C ) Laccase-catalysed reactions between quinones and substituted 4-amino-4H-1,2,4-triazolo-3-thiols [ 98 ]. …”

Section: Figures Schemes and Tablementioning

confidence: 99%

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Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

2021

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Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.

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Section: Application Of Laccases In Bio-oxidative Synthesis Of Heterocyclic Compoundsmentioning

confidence: 99%

Section: Application Of Laccases In Bio-oxidative Synthesis Of Heterocyclic Compoundsmentioning

confidence: 99%

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Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

2021

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“…The yield of most of the compounds synthesized by laccase Suberase was lower than those previously synthesized by other commercial laccases[Hajdok et al [49]; Witayakran et al(2007);Witayakran and Ragauskas (2009)]. Nonetheless, two of the Suberase laccase-synthesized compounds reported byWellington et al [32] were obtained in higher yields than those obtained by fungal crude extract, chemical or electrochemical methods[43][44][45][46][47]. The contribution of Wellington et al [32], with respect to the other authors that synthesized the same 5,6-dihydroxylated benzo[b]furans (Figure 4Ac), is the evaluation of cytostatic and cytotoxic effect of the compounds against TK10 (renal), UACC62 (melanoma), MCF7 (breast), HeLA (cervical) cancer cell lines.…”

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confidence: 88%

Dioxygen Activation by Laccases: Green Chemistry for Fine Chemical Synthesis

2018

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Laccases are enzymes with attractive features for the synthesis of fine chemicals. The friendly reaction conditions of laccases and their high conversion and selectivity make them particularly suitable for green methods of synthesis. In addition, laccases are enzymes with broad substrate variability, ease of production, and no need of cofactors or aggressive oxidizing agents. Among molecules oxidized by laccases are polycyclic aromatic hydrocarbons, azo dyes, pesticides, phenols, and pharmaceuticals. This article reviews the laccase-mediated oxidation of fine chemicals for the production of biologically active compounds. The main aspects of the enzymatic oxidation are summarized; potentials and limitations are identified and proposals to develop more robust catalysts are analyzed.

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“…The enzyme-mediated oxidations demand only atmospheric oxygen and no depletive cofactors such as NADPH. Laccases oxidize substrates by one-electron reactions via four copper atoms, which are situated in the catalytic center. − The enzyme can oxidize a broad range of substrates such as phenols, thiols, or amines. − The laccase-mediated oxidations result in the formation of radicals that can undergo three different reaction mechanisms. The first mechanism involves the cleavage, while the second and third mechanisms involve coupling/bond formation.…”

Section: Introductionmentioning

confidence: 99%

Ring-Closure Mechanisms Mediated by Laccase to Synthesize Phenothiazines, Phenoxazines, and Phenazines

et al. 2020

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The green and environmentally friendly synthesis of highly valuable organic substances is one possibility for the utilization of laccases (EC 1.10.3.2). As reactants for the herein described syntheses, different o-substituted arylamines or arylthiols and 2,5-dihydroxybenzoic acid and its derivatives were used. In this way, the formation of phenothiazines, phenoxazines, and phenazines was achieved in aqueous solution mediated by the laccase of Pycnoporus cinnabarinus in the presence of oxygen. Two types of phenothiazines (3-hydroxy- and 3-oxo-phenothiazines) formed in one reaction assay were described for the first time. The cyclization reactions yielded C–N, C–S, or C–O bonds. The syntheses were investigated with regard to the substitution pattern of the reaction partners. Differences in C–S and C–N bond formations without cyclization are discussed.

show abstract

Ecofriendly syntheses of phenothiazones and related structures facilitated by laccase – a comparative study

Cited by 13 publications

References 51 publications

Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

Dioxygen Activation by Laccases: Green Chemistry for Fine Chemical Synthesis

Ring-Closure Mechanisms Mediated by Laccase to Synthesize Phenothiazines, Phenoxazines, and Phenazines

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