Solid-Phase Synthesis of Amino Acid Derived N-Unsubstituted Pyrazoles via Sydnones

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• 作者：Kirsi Harju ; Johanna Vesterinen ; Jari Yli-Kauhaluoma
• 刊名：Organic Letters
• 出版年：2009
• 出版时间：May 21, 2009
• 年：2009
• 卷：11
• 期：10
• 页码：2219-2221
• 全文大小：130K
• 年卷期：v.11,no.10(May 21, 2009)
• ISSN：1523-7052

文摘

A new method to synthesize N-unsubstituted pyrazoles on a solid support is described. The solid support acts as a protecting group for the amino acid. N-Protected amino acid is N-nitrosated, and the subsequent treatment with acetic anhydride in a microwave reactor yields mesoionic sydnones that react in situ in 1,3-dipolar cycloaddition reactions with alkynes. Traceless cleavage of the products gives N-unsubstituted pyrazoles in high overall yields.