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

Research output: Contribution to journalArticle

33 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 languageEnglish (US)
Pages (from-to)901-906
Number of pages6
JournalTetrahedron
Volume60
Issue number4
DOIs
StatePublished - Jan 19 2004

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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