Synthesis of β-tosylethylhydrazine and its use in preparation of N-protected pyrazoles and 5-aminopyrazoles

David M. Dastrup; Amy H. Yap; Steven M. Weinreb; James R. Henry; Andrew J. Lechleiter

doi:10.1016/j.tet.2003.11.046

Synthesis of β-tosylethylhydrazine and its use in preparation of N-protected pyrazoles and 5-aminopyrazoles

David M. Dastrup, Amy H. Yap, Steven M. Weinreb, James R. Henry, Andrew J. Lechleiter

Chemistry

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

36 Scopus citations

Abstract

β-Tosylethylhydrazine (6) can be prepared efficiently in one step from commercially available p-tolyl vinyl sulfone (7) and hydrazine hydrate. This hydrazine reacts with both 1,3-diketones and conjugated ynones in glacial acetic acid to provide a variety of N-tosylethyl-protected (TSE) pyrazoles in good yields. The TSE group can be removed from the pyrazoles using potassium t-butoxide in THF at -30°C-rt. In addition, hydrazine 6 condenses with β-ketonitriles and β-aminoacrylonitriles to afford 5-aminopyrazoles, which can be deprotected by brief treatment with NaOEt in EtOH/DMSO at 45°C.

Original language	English (US)
Pages (from-to)	901-906
Number of pages	6
Journal	Tetrahedron
Volume	60
Issue number	4
DOIs	https://doi.org/10.1016/j.tet.2003.11.046
State	Published - Jan 19 2004

All Science Journal Classification (ASJC) codes

Biochemistry
Drug Discovery
Organic Chemistry

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10.1016/j.tet.2003.11.046

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title = "Synthesis of β-tosylethylhydrazine and its use in preparation of N-protected pyrazoles and 5-aminopyrazoles",

abstract = "β-Tosylethylhydrazine (6) can be prepared efficiently in one step from commercially available p-tolyl vinyl sulfone (7) and hydrazine hydrate. This hydrazine reacts with both 1,3-diketones and conjugated ynones in glacial acetic acid to provide a variety of N-tosylethyl-protected (TSE) pyrazoles in good yields. The TSE group can be removed from the pyrazoles using potassium t-butoxide in THF at -30°C-rt. In addition, hydrazine 6 condenses with β-ketonitriles and β-aminoacrylonitriles to afford 5-aminopyrazoles, which can be deprotected by brief treatment with NaOEt in EtOH/DMSO at 45°C.",

author = "Dastrup, {David M.} and Yap, {Amy H.} and Weinreb, {Steven M.} and Henry, {James R.} and Lechleiter, {Andrew J.}",

note = "Funding Information: The work at Penn State was supported by a research grant from the National Institutes of Health (CA-34303), and by NSF grant CHE-0131112 for purchase of an X-ray diffractometer. We thank Dr. Hemant Yennawar (Penn State Small Molecule X-ray Crystallographic Facility) for determining the structure of compound 12a . ",

year = "2004",

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doi = "10.1016/j.tet.2003.11.046",

language = "English (US)",

volume = "60",

pages = "901--906",

journal = "Tetrahedron",

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T1 - Synthesis of β-tosylethylhydrazine and its use in preparation of N-protected pyrazoles and 5-aminopyrazoles

AU - Dastrup, David M.

AU - Yap, Amy H.

AU - Weinreb, Steven M.

AU - Henry, James R.

AU - Lechleiter, Andrew J.

N1 - Funding Information: The work at Penn State was supported by a research grant from the National Institutes of Health (CA-34303), and by NSF grant CHE-0131112 for purchase of an X-ray diffractometer. We thank Dr. Hemant Yennawar (Penn State Small Molecule X-ray Crystallographic Facility) for determining the structure of compound 12a .

PY - 2004/1/19

Y1 - 2004/1/19

N2 - β-Tosylethylhydrazine (6) can be prepared efficiently in one step from commercially available p-tolyl vinyl sulfone (7) and hydrazine hydrate. This hydrazine reacts with both 1,3-diketones and conjugated ynones in glacial acetic acid to provide a variety of N-tosylethyl-protected (TSE) pyrazoles in good yields. The TSE group can be removed from the pyrazoles using potassium t-butoxide in THF at -30°C-rt. In addition, hydrazine 6 condenses with β-ketonitriles and β-aminoacrylonitriles to afford 5-aminopyrazoles, which can be deprotected by brief treatment with NaOEt in EtOH/DMSO at 45°C.

AB - β-Tosylethylhydrazine (6) can be prepared efficiently in one step from commercially available p-tolyl vinyl sulfone (7) and hydrazine hydrate. This hydrazine reacts with both 1,3-diketones and conjugated ynones in glacial acetic acid to provide a variety of N-tosylethyl-protected (TSE) pyrazoles in good yields. The TSE group can be removed from the pyrazoles using potassium t-butoxide in THF at -30°C-rt. In addition, hydrazine 6 condenses with β-ketonitriles and β-aminoacrylonitriles to afford 5-aminopyrazoles, which can be deprotected by brief treatment with NaOEt in EtOH/DMSO at 45°C.

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Synthesis of β-tosylethylhydrazine and its use in preparation of N-protected pyrazoles and 5-aminopyrazoles

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