Investigation of the scope of a [3+2] cycloaddition approach to isoxazole boronic esters

Moore, Jane E.; Davies, Mark W.; Goodenough, Katharine M.; Wybrow, Robert A. J.; York, Mark; Johnson, Christopher N.; Harrity, Joseph P. A.

doi:10.1016/j.tet.2005.05.015

Cited by 79 publications

(30 citation statements)

References 24 publications

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“…[164,165] Scheme 77. In these cases, the organoboranes were not synthesized by a metalation-quenching strategy but directly introduced through cyclization of nitrile oxides 228 and alkynylboronic acid esters.…”

Section: Suzuki-miyaura Reactionsupporting

confidence: 62%

Cross‐Coupling Reactions on Azoles with Two and More Heteroatoms

et al. 2006

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Recent progress in the field of transition‐metal‐catalyzed cross‐coupling reactions on various azole systems is summarized. Most important C–C‐ and C–X‐bond formation methodologies (Negishi, Suzuki–Miyaura, Stille, Kumada–Corriu–Tamao, Hiyama, Sonogashira, Heck, C–H activation) are reviewed and discussed for the imidazole, oxazole, thiazole, pyrazole, isoxazole, and isothiazole system, as well as for azoles with more than two heteroatoms. This review covers the literature that appeared in the past ten years up to the end of 2005 with corresponding azoles used either as metal organyl or halide (including triflates and some other less frequently applied leaving groups); literature describing azole structures only as ligands was not included.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Suzuki-miyaura Reactionsupporting

confidence: 62%

Cross‐Coupling Reactions on Azoles with Two and More Heteroatoms

et al. 2006

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“…Valdecoxib 1 and its mesityl-substituted analogue 114 were synthesized by the cycloaddition of alkyne 113 with benzo- and mesitonitrile oxides 94 to afford intermediate isoxazole-4-boronates 95 . 62 These isoxazole-4-boronates 95 when subjected to Suzuki coupling reaction with p bromobenzene sulfonamide furnished the targeted drug valdecoxib 1 and its mesityl-substituted analogue 114 in excellent yields (Scheme 29). The reaction protocol is of greater significance in the synthesis of valdecoxib analogues (especially 114 ) compared to earlier report, 31 where the reaction suffered from undesired chlorosulfonation, steric effects, and low product formation.…”

Section: 3 13-dipolar Cycloadditionsmentioning

confidence: 99%

Recent methodologies toward the synthesis of valdecoxib: A potential 3,4-diarylisoxazolyl COX-II inhibitor

Dadiboyena

Nefzi

2010

European Journal of Medicinal Chemistry

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Non-steroidal anti-inflammatory drugs are widely used therapeutic agents in the treatment of inflammation, pain and fever. Cyclooxygenase catalyzes the initial step of biotransformation of arachidonic acid to prostanoids, and exist as three distinct isozymes; COX-I, COX-II and COX-III. Selective COX-II inhibitors are a class of potential anti-inflammatory, analgesic, and antipyretic drugs with reduced gastrointestinal (GI) side effects compared to nonselective inhibitors. 3,4-diarylisoxazole scaffold is recurrently found in a wide variety of NSAIDs, protein kinase inhibitors, hypertensive agents, and estrogen receptor (ER) modulators. In the present review, we document on the recent synthetic strategies of 3,4-diarylisoxazolyl scaffolds of valdecoxib and its relevant structural analogues.

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“…In addition, isoxazoles substituted with a pinacol-derived boronic esters at C-3 have been obtained by [3+2] cycloaddition involving nitrile oxides and alkynylboronates. 240 Moreover, 3-benzyloxyisothiazole has been transformed into a isothiazo-5-yl boronic ester, intended to crosscoupling reactions, via direct lithiation using LDA followed by boronic ester formation and transesterification. 241 However, the yield was very low, probably due to the limited stability of the 5-lithio-3-benzyloxyisothiazole intermediate.…”

Section: Scheme 35mentioning

confidence: 99%