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

…, AH Yap, SM Weinreb, JR Henry, AJ Lechleiter

Index: Dastrup, David M.; Yap, Amy H.; Weinreb, Steven M.; Henry, James R.; Lechleiter, Andrew J. Tetrahedron, 2004 , vol. 60, # 4 p. 901 - 906

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Citation Number: 29

Abstract

β-Tosylethylhydrazine () can be prepared efficiently in one step from commercially available p-tolyl vinyl sulfone () 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 condenses with β- ...