An economic, simple and convenient synthesis of 2-aryl/heteroaryl/styryl/alkylbenzothiazoles using SiO2–HNO3

Kumar, Parvin; Bhatia, Rimpy; Kumar, Dinesh; Kamboj, Ramesh C.; Kumar, Suresh; Kamal, Raj; Kumar, Ramesh

doi:10.1007/s11164-013-1529-x

Cited by 11 publications

(7 citation statements)

References 42 publications

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“…Owing to the interesting properties of their derivatives, functionalization of benzothiazoles to give 2‐substituted benzothiazoles have attracted much attention in recent years. The conventional methods for synthesis of 2‐substituted benzothiazoles includes using metals as catalysts for intramolecular cyclization reactions and also the condensation of 2‐aminothiophenol with alcohols, aldehydes, ketones, carboxylic acids, halides, ammonium triflates, β‐oxodithioesters and amines . However, having harsh and hazardous reaction conditions, use of expensive reagents and metal catalysts or strong acidic or oxidative conditions, and also tedious workup procedures for separation of the pure products are the disadvantages for most of these transformations .…”

Section: Introductionmentioning

confidence: 99%

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

Khalili

Etemadi‐Davan

Banazadeh

2017

Applied Organom Chemis

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In this report, we introduced Graphene oxide‐iron oxide (GO‐Fe3O4) nanocomposites as a heterogeneous catalyst for arylation/alkylation of benzothiazoles with aldehydes and benzylic alcohols in the presence of diisopropyl azodicarboxylate (DIAD) as an oxidant which exclusively produced 2‐aryl (alkyl)‐1H–benzothizoles in moderate to excellent yields. The absence of precious metals and toxic solvent, easy product isolation, and recyclability of the GO‐Fe3O4 with no loss of activity are notable advantages of this method.

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Section: Introductionmentioning

confidence: 99%

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

Khalili

Etemadi‐Davan

Banazadeh

2017

Applied Organom Chemis

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“…SiO 2 -HNO 3 mediated synthesis of 2-substituted benzothiazoles. [221] oxidant (Scheme 41). Solvent-free condensation reaction resulted in longer reaction time and poor yield.…”

Section: Silica-supported Reagentsmentioning

confidence: 99%

“…Kumar and coauthors [221] developed a new, mild and efficient protocol for the synthesis of 2‐substituted benzothiazoles (19) using SiO 2 ‐HNO 3 . In order to establish the optimized reaction conditions, the reaction was explored under solvent‐free conditions as well as in different solvents such as DCM, ACN, MeOH with varying amounts of catalyst.…”

Section: Applications Of Solid‐supported Reagents For the Synthesis Of 2‐substituted Benzothiazolesmentioning

confidence: 99%

Solid‐Supported Materials‐Based Synthesis of 2‐Substituted Benzothiazoles: Recent Developments and Sanguine Future

et al. 2021

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Benzothiazole and its derivatives have been manifested as an optimistic scaffold due to their immense biological importance. Several methodologies have been reported as modifications after the first report of 2-substituted benzothiazole. Among them, many involve a shift from the conventional synthetic approach by utilizing different catalytic systems. Moreover, synthetic methodologies focused on improvements in terms of product yield, reaction duration, use of environmentally benign conditions and simplified workup procedures predominate among the recently developed approaches. Solid-phase organic synthesis received considerable attention with the pioneering findings of Merrifield's solid-phase peptide synthesis in 1963. A diverse range of organic, inorganic and organic-inorganic substances have been utilized as polymeric solid supports in various catalytic applications. The recyclability and reusability of the immobilized catalysts over consecutive cycles establish them as an attractive alternative over conventional catalytic systems from the environment as well as industrial perspective. The present review summarizes the recent developments in the environmentally benign synthesis of benzothiazole derivatives using supported reagents. Different solid supports along with their catalytic application, mechanistic perspective and substrate tolerance have been discussed comprehensively.

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“…So, scientists are looking toward alternative methods with milder and cleaner reaction conditions, simpler work up, superior yield and decreased reaction times. An appealing strategy toward this end is the development of solid‐supported reagents . Recently silica‐supported molybdic acid is used for the regioselective synthesis of 1,3,5‐trisubstituted pyrazoles with 2,4‐dinitro substituent at N‐phenyl ring .…”

Section: Introductionmentioning

confidence: 99%

A Serendipitous Synthesis: SiO₂‐HNO₃ Mediated Oxidative Aromatization and Regioselective Nitration of 1,3,5‐Trisubstituted‐4,5‐Dihydro‐1H‐Pyrazoles

et al. 2019

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Research often leads to unprecedented results that open the gates for new methodologies. We report herein the oxidative aromatization and serendipitous regioselective nitration of 1,3,5-trisubstituted-4,5-dihydro-1H-pyrazoles under mild reaction conditions using SiO 2 -HNO 3 as an oxidizing agent to afford 1,3,5-trisubstituted pyrazoles with high regioselectivity. Here SiO 2 -HNO 3 acts as a nitrating agent along with oxidizing property. SiO 2 -HNO 3 is cheap, easy to prepare, eco-friendly and practically applicable catalyst.[a] Dr.

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An economic, simple and convenient synthesis of 2-aryl/heteroaryl/styryl/alkylbenzothiazoles using SiO2–HNO3

Cited by 11 publications

References 42 publications

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

Solid‐Supported Materials‐Based Synthesis of 2‐Substituted Benzothiazoles: Recent Developments and Sanguine Future

A Serendipitous Synthesis: SiO₂‐HNO₃ Mediated Oxidative Aromatization and Regioselective Nitration of 1,3,5‐Trisubstituted‐4,5‐Dihydro‐1H‐Pyrazoles

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An economic, simple and convenient synthesis of 2-aryl/heteroaryl/styryl/alkylbenzothiazoles using SiO2–HNO3

Cited by 11 publications

References 42 publications

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe3O4 hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe3O4 hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

Solid‐Supported Materials‐Based Synthesis of 2‐Substituted Benzothiazoles: Recent Developments and Sanguine Future

A Serendipitous Synthesis: SiO2‐HNO3 Mediated Oxidative Aromatization and Regioselective Nitration of 1,3,5‐Trisubstituted‐4,5‐Dihydro‐1H‐Pyrazoles

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2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

2‐Arylation/alkylation of benzothiazoles using superparamagneticgraphene oxide‐Fe₃O₄ hybrid material as a heterogeneous catalystwith diisopropyl azodicarboxylate (DIAD) as an oxidant

A Serendipitous Synthesis: SiO₂‐HNO₃ Mediated Oxidative Aromatization and Regioselective Nitration of 1,3,5‐Trisubstituted‐4,5‐Dihydro‐1H‐Pyrazoles