Niobium-promoted reaction of α-phenylglyoxylic acid with ortho-functionalized anilines: synthesis of 2-arylbenzothiazoles and 3-aryl-2H-benzo[b][1,4]benzoxazin-2-ones

Penteado, Filipe; Vieira, Marcelo M.; Perin, Gelson; Alves, Diego; Jacob, Raquel G.; Santi, Claudio; Lenardão, Eder J.

doi:10.1039/c6gc02495e

Cited by 40 publications

(18 citation statements)

References 58 publications

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“…In 2016, Lenardão and co‐workers published a study focused on the synthesis of 3‐substituted 2 H ‐benzo[ b ][1,4]benzoxazine‐2‐ones 76 and 2‐substituted benzothiazoles 77 , through a niobium‐catalyzed reaction between α‐keto acids 46 and ortho ‐functionalized anilines 27 , using PEG‐400 as solvent (Scheme ).…”

Section: Synthesis Of Organochalcogen Compoundsmentioning

confidence: 99%

Ultrasound‐Assisted Multicomponent Reactions, Organometallic and Organochalcogen Chemistry

et al. 2018

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In the last two decades, the search for sustainability in chemical reactions has attached a lot of attention. In this focus review, the use of ultrasound (US) as an alternative energy source in organic synthesis is presented. The improvement of the performance of chemical reactions due to the cavitation effect has been previously studied and described. The use of US guarantees often higher yields than other green methodologies, as microwave or ball milling. The impressive positive effect of US in organic synthesis are demonstrated in this review mainly in organometallic and multi-component reactions (MCRs), aimed to prepare bioactive compounds. A particular attention is dedicated to the US-assisted synthesis of valuable organochalcogen compounds with pharmacological activity.[a] F.

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Section: Synthesis Of Organochalcogen Compoundsmentioning

confidence: 99%

Ultrasound‐Assisted Multicomponent Reactions, Organometallic and Organochalcogen Chemistry

et al. 2018

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“…We recently explored this particular feature of α‐keto acids by synthesizing 2‐arylbenzothiazoles and 3‐substituted benzoxazin‐2‐ones through the oxidative decarboxylation of α‐keto acids catalyzed by ammonium niobium oxalate (ANO) in the presence of PEG‐400 as the solvent. This protocol afforded the desired products in moderate to good yields within short reaction times …”

Section: Introductionmentioning

confidence: 99%

α‐Keto Acids as Acylating Agents in the Synthesis of 2‐Substituted Benzothiazoles and Benzoselenazoles

et al. 2017

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Herein, we report the first decarboxylative oxidation of α‐keto acids that is promoted by sodium metabisulfite (Na2S2O5) to obtain 2‐substituted benzothiazoles and benzoselenazoles. Diaryl disulfides and diselenides were used as chalcogen sources, and the desired products were obtained in moderate to excellent yields. This protocol does not require an inert gas, transition metals, or harsh reaction conditions, and CO2 is released as an environmentally benign coproduct. The presence of Na2S2O5 was essential to guarantee that the reaction reached completion and afforded maximum product yields.

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“…developed an electrochemical decarboxylative method for the 2‐substituted benzothiazoles synthesis using Pt−Pt undivided cell in 0.2 M NH 4 ClO 4 as supporting electrolyte . In due course, Penteado and Laha et al . independently synthesized benzothiazoles by heating α‐keto acids and 2‐aminothiophenol under ammonium niobium oxalate‐catalyzed and K 2 S 2 O 8 ‐mediated conditions respectively (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Benzothiazoles via Photooxidative Decarboxylation of α‐Keto Acids

et al. 2020

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Herein, synthesis of benzothiazoles via decarboxylative cross-coupling between α-keto acids and 2aminothiophenols under blue LED irradiation without using any photocatalyst or metal at room temperature is described. The formation of benzothiazole is driven by the EDA (electron donor-acceptor) complex formed between α-keto acid and 2-aminothiophenol. This methodology gives easy access to 2-substituted and -unsubstituted benzothiazoles in moderate to good yields. α-Keto acids and 2-aminothiophenols bearing different functional groups were easily transformed under the given conditions.

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Niobium-promoted reaction of α-phenylglyoxylic acid with ortho-functionalized anilines: synthesis of 2-arylbenzothiazoles and 3-aryl-2H-benzo[b][1,4]benzoxazin-2-ones

Abstract: Ammonium niobium oxalate promotes the reaction of α-phenylglyoxylic acid with o-functionalized anilines for the synthesis of benzothiazoles and benzoxazin-2-ones.

Cited by 40 publications

References 58 publications

Ultrasound‐Assisted Multicomponent Reactions, Organometallic and Organochalcogen Chemistry

Ultrasound‐Assisted Multicomponent Reactions, Organometallic and Organochalcogen Chemistry

α‐Keto Acids as Acylating Agents in the Synthesis of 2‐Substituted Benzothiazoles and Benzoselenazoles

Synthesis of Benzothiazoles via Photooxidative Decarboxylation of α‐Keto Acids

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