Interceptive [4 + 1] annulation of in situ generated 1,2-diaza-1,3-dienes with diazo esters: direct access to substituted mono-, bi-, and tricyclic 4,5-dihydropyrazoles

Orazio A Attanasi; Lucia De Crescentini; Gianfranco Favi; Fabio Mantellini; Serena Mantenuto; Simona Nicolini

doi:10.1021/jo5016097

Interceptive [4 + 1] annulation of in situ generated 1,2-diaza-1,3-dienes with diazo esters: direct access to substituted mono-, bi-, and tricyclic 4,5-dihydropyrazoles

J Org Chem. 2014 Sep 5;79(17):8331-8. doi: 10.1021/jo5016097. Epub 2014 Aug 12.

Authors

Orazio A Attanasi¹, Lucia De Crescentini, Gianfranco Favi, Fabio Mantellini, Serena Mantenuto, Simona Nicolini

Affiliation

¹ Department of Biomolecular Sciences, Section of Organic Chemistry and Organic Natural Compounds, University of Urbino "Carlo Bo" , Via I Maggetti 24, 61029 Urbino, Italy.

PMID: 25116326
DOI: 10.1021/jo5016097

Abstract

In situ derived acyclic and cyclic 1,2-diaza-1,3-dienes (DDs) were engaged in interceptive [4 + 1] annulation strategy with diazo esters (DEs). The catalytic activity of inexpensive copper(II) chloride allows the direct synthesis of mono-, bi-, and tricyclic 4,5-dihydropyrazole-5-carboxylic acid derivatives in a process that circumvents the use of an anhydrous and inert atmosphere.