A Simple and Convenient Synthesis of 5-Substituted Benzoxazoles

Kunz, Kenneth R.; Taylor, Ethan Will; Hutton, H. M.; Blackburn, B. J.

doi:10.1080/00304949009356332

Cited by 18 publications

(6 citation statements)

References 16 publications

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“…Liquid reagents were flushed with argon prior to use. ( iPr2 PCP iPr2 )PdCl, ( iPr2 POCOP iPr2 )PdCl, 3-hydroxybenzyl bromide, 5-methylbenzoxazole, 5-arylazoles, and 6-substituted benzothiazole were synthesized according to previously described procedures. All other chemicals were obtained from commercial sources and were used without further purification.…”

Section: Experimental Sectionmentioning

confidence: 99%

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway

et al. 2016

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Pincer-based ( R2 POCN R ′ 2 )PdCl complexes along with CuI cocatalyst catalyze the arylation of azoles with aryl iodides to give the 2-arylated azole products. Herein, we report an extensive mechanistic investigation for the direct arylation of azoles involving a well-defined and highly efficient ( iPr2 POCN Et2 )PdCl (2a) catalyst, which emphasizes a rare Pd II −Pd IV −Pd II redox catalytic pathway. Kinetic studies and deuterium labeling experiments indicate that the C−H bond cleavage on azoles occurs via two distinct routes in a reversible manner. Controlled reactivity of the catalyst 2a underlines the iodo derivative ( iPr2 POCN Et2 )PdI (3a) to be the resting state of the catalyst. The intermediate species ( iPr2 POCN Et2 )Pd-benzothiazolyl (4a) has been isolated and structurally characterized. A determination of reaction rates of compound 4a with electronically different aryl iodides has revealed the kinetic significance of the oxidative addition of the C(sp 2 )−X electrophile, aryl iodide, to complex 4a. Furthermore, the reactivity behavior of 4a suggests that the arylation of benzothiazole proceeds via an oxidative addition/ reductive elimination pathway involving a ( iPr2 POCN Et2 )Pd IV (benzothiazolyl)(Ar)I species, which is strongly supported by DFT calculations.

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Section: Experimental Sectionmentioning

confidence: 99%

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway

et al. 2016

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“…In 2009, Lee et al reported a simple and effective procedure for the generation of benzoxazoles and oxazoles via the one-pot reduction-triggered heterocyclization reaction. Indium/acetic acid promoted the reaction of 2-nitrophenols with trimethyl orthoesters in refluxing benzene to produce benzoxazoles 432–434 in 50–98% yields in a 1 h period. In a similar manner, 1-aryl-2-nitroethanones upon treatment with trimethyl orthobenzoate using In/AcOH in refluxing acetonitrile afforded oxazoles in 1 h in 46–72% yields.…”

Section: Orthoester Reactions In Organic Solventsmentioning

confidence: 99%

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

Khademi

Nikoofar

2020

RSC Adv.

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“…A simple and convenient synthesis of 5-substituted benzoxazoles has been reported by Kunz et al [33]. 5-Substituted benzoxazoles (63) are prepared from 4-substituted 2-aminophenols by the treatment with trimethyl orthoformate and concentrated aqueous hydrochloric acid.…”

Section: Jyothi and Merugumentioning

confidence: 99%

An Update on the Synthesis of Benzoxazoles

Jyothi

Merugu

2017

Asian J Pharm Clin Res

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Benzoxazoles being structurally similar to bases adenine and guanine interact with biomolecules present in living systems. These compounds possess antimicrobial, central nervous system activities, antihyperglycemic potentiating activity, analgesic, and anti-inflammatory activity. It can also be used as starting material for other bioactive molecules. Modifications in structure and the biological profiles of new generations of benzoxazoles were found to be more potent with enhanced biological activity. Considering all these, we have prepared this review and discussed the synthesis and biological activities of benzoxazoles.

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A Simple and Convenient Synthesis of 5-Substituted Benzoxazoles

Cited by 18 publications

References 16 publications

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

An Update on the Synthesis of Benzoxazoles

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A Simple and Convenient Synthesis of 5-Substituted Benzoxazoles

Cited by 18 publications

References 16 publications

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a PdII–PdIV–PdII Pathway

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a PdII–PdIV–PdII Pathway

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

An Update on the Synthesis of Benzoxazoles

Contact Info

Product

Resources

About

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway

Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a Pd^II–Pd^IV–Pd^II Pathway