An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

Pankaj V. Khairnar; Tsai Hui Lung; Yi Jung Lin; Chi Yi Wu; Srinivasa Rao Koppolu; Athukuri Edukondalu; Praneeth Karanam; Wenwei Lin

doi:10.1021/acs.orglett.9b01395

An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

Pankaj V. Khairnar, Tsai Hui Lung, Yi Jung Lin, Chi Yi Wu, Srinivasa Rao Koppolu, Athukuri Edukondalu, Praneeth Karanam, Wenwei Lin

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

23 Citations (Scopus)

Abstract

α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.

Original language	English
Pages (from-to)	4219-4223
Number of pages	5
Journal	Organic Letters
Volume	21
Issue number	11
DOIs	https://doi.org/10.1021/acs.orglett.9b01395
Publication status	Published - 2019 Jun 7

ASJC Scopus subject areas

Biochemistry
Physical and Theoretical Chemistry
Organic Chemistry

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An Intramolecular Wittig Approach toward Heteroarenes : Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes. / Khairnar, Pankaj V.; Lung, Tsai Hui; Lin, Yi Jung; Wu, Chi Yi; Koppolu, Srinivasa Rao; Edukondalu, Athukuri; Karanam, Praneeth; Lin, Wenwei.

In: Organic Letters, Vol. 21, No. 11, 07.06.2019, p. 4219-4223.

Research output: Contribution to journal › Article › peer-review

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title = "An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes",

abstract = "α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.",

author = "Khairnar, {Pankaj V.} and Lung, {Tsai Hui} and Lin, {Yi Jung} and Wu, {Chi Yi} and Koppolu, {Srinivasa Rao} and Athukuri Edukondalu and Praneeth Karanam and Wenwei Lin",

note = "Funding Information: We thank the Ministry of Science and Technology of the Republic of China (MOST 107-2628-M-003-001-MY3) for financial support..",

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AU - Khairnar, Pankaj V.

AU - Lung, Tsai Hui

AU - Lin, Yi Jung

AU - Wu, Chi Yi

AU - Koppolu, Srinivasa Rao

AU - Edukondalu, Athukuri

AU - Karanam, Praneeth

AU - Lin, Wenwei

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AB - α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.

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An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes

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