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Note | Regular issue | Vol 71, No. 1, 2007, pp.189-196
Published online, 1st December, 2006
DOI: 10.3987/COM-06-10935
Hafnium Chloride Catalyzed Conjugate Addition of Pyrrole, Pyrazole and Imidazole to α,β-Unsaturated Ketones

Sachiko Aburatani, Motoi Kawatsura, and Jun’ichi Uenishi*

*Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan

Abstract

Pyrrole, pyrazole and imidazole undergo conjugate addition with α,β-unsaturated ketones in the presence of a catalytic amount of hafnium chloride at room temperature. Although the reaction of pyrrole gave 2,5-substituted C-adduct mainly, those of pyrazole and imidazole gave the corresponding N-adducts in excellent yields.