Brønsted Acid Mediated Nucleophilic Functionalization of Amides through Stable Amide C−N Bond Cleavage; One‐Step Synthesis of 2‐Substituted Benzothiazoles

Maity, Srabani; Roy, Arnab; Duari, Surajit; Biswas, S.; Elsharif, Asma M.; Biswas, Srijit

doi:10.1002/ejoc.202100645

Cited by 10 publications

(1 citation statement)

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“…[ 14 ] Several conventional methods documented the fabrication of benzothiazoles from simple condensation of carbonyl compounds, amides, and carboxylic acid derivatives with 2‐aminothiophenol under acidic conditions. [ 15–17 ] Similarly, benzothiazoles were also achieved by the coupling of 2‐aminothiophenol and alcohols in the presence of oxidants such as 2‐iodoxybenzoic acid (IBX), [ 18 ] propylphosphonic anhydride (T3P)/DMSO, [ 19 ] and 2,2,6,6‐tetramethylpiperidine oxide (TEMPO). [ 20 ] Further, the Fe(II) catalyst‐mediated synthesis of benzothiazoles from aminophenol and alcohol in 36 h was reported.…”

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confidence: 99%

Synthesis and structural characterization of palladium pincer complexes: Sustainable synthesis of benzothiazoles

Anandaraj

Saranya

Ramesh

2023

Applied Organom Chemis

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An efficient Pd(II)N^N^S pincer type catalysts‐promoted sustainable construction of pharmaceutically important benzothiazole derivatives from primary alcohols and 2‐aminothiophenol via acceptorless dehydrogenative coupling (ADC) method has been described. The newly synthesized ligand L2 and the Pd(II) complexes in addition to L1 and L3 were characterized by analytical and Fourier transform infrared spectroscopy (FT‐IR), UV–visible (UV–vis), and nuclear magnetic resonance (NMR) spectral techniques. Further, the ORTEP views of the complexes 2 and 3 were established by a single crystal XRD study, which evidenced the coordination of the thiosemicarbazone ligands and disclose the square‐planar geometry around the Pd(II) ion. The present homogeneous catalytic system involves synthesizing a range of benzothiazoles via C−S and C−N bond formation with excellent yields up to 93%. The described methodology employs a sustainable, highly abundant, and inexpensive alcohol as starting material using 1 mol% catalyst loading, and water and hydrogen gas are the only by‐products. Furthermore, a plausible mechanism involving in situ aldehyde formation via dehydrogenation of primary alcohols has been proposed. A large‐scale synthesis of 2‐(4‐methoxyphenyl)benzo[d]thiazole illustrates the synthetic utility of the present catalytic protocol.

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Section: Introductionmentioning

confidence: 99%

Synthesis and structural characterization of palladium pincer complexes: Sustainable synthesis of benzothiazoles

Anandaraj

Saranya

Ramesh

2023

Applied Organom Chemis

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Regioselective N‐Functionalization of Tautomerizable Heterocycles through Methyl Trifluoromethanesulfonate‐Catalyzed Substitution of Alcohols and Alkyl Group Migrations

et al. 2022

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A catalytic synthetic strategy has been developed combining two protocols, such as, direct nucleophilic substitution of alcohols followed by X‐ to N‐ alkyl group migration (X=O, S) to access N‐functionalized benzoxazolones, benzothiazolethiones, indolinone, benzoimidazolethiones, and pyridinones derivatives. Methyl trifluoromethanesulfonate (MeOTf) was found to catalyze the reaction, which revealed the catalytic property of MeOTf. A mechanism was established through experiments as well as DFT calculations wherein the −OH group of alcohols were converted to the corresponding −OMe groups and in situ generated TfOH. The −OMe groups produced underwent TfOH catalyzed −X alkylation (X=O, S) of the heterocycles followed by −X‐ to −N‐alkyl group migrations in a single step.

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Regioselective Transition Metal-Free Catalytic Ring Opening of 2H-Azirines by Phenols and Naphthols; One-Pot Access to Benzo- and Naphthofurans

Roy,

Biswas,

Duari

et al. 2023

J. Org. Chem.

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Benzofuran and naphthofuran derivatives are synthesized from readily available phenols and naphthols. Regioselective ring openings of 2H-azirine followed by in situ aromatization using a catalytic amount of Brønsted acid have established the novelty of the methodology. The involvement of a series of 2H-azirines with a variety of phenols, 1-naphthols, and 2-naphthols showed the generality of the protocol. In-depth density functional theory calculations revealed the reaction mechanism with the energies of the intermediates and transition states of a model reaction. An alternate pathway of the mechanism has also been proposed with computer modeling.

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Brønsted Acid Mediated Nucleophilic Functionalization of Amides through Stable Amide C−N Bond Cleavage; One‐Step Synthesis of 2‐Substituted Benzothiazoles

Abstract: information for this article is given via a link at the end of the document. Scheme 1. Previous reports of alcoholysis of amides, nucleophilic substitution of alcohols and this work.

Cited by 10 publications

References 39 publications

Synthesis and structural characterization of palladium pincer complexes: Sustainable synthesis of benzothiazoles

Synthesis and structural characterization of palladium pincer complexes: Sustainable synthesis of benzothiazoles

Regioselective N‐Functionalization of Tautomerizable Heterocycles through Methyl Trifluoromethanesulfonate‐Catalyzed Substitution of Alcohols and Alkyl Group Migrations

Regioselective Transition Metal-Free Catalytic Ring Opening of 2H-Azirines by Phenols and Naphthols; One-Pot Access to Benzo- and Naphthofurans

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