Ring transformation of spirocyclopropanepyrazoles into pyrano[2,3-c]pyrazoles

An approach to pyrano[2,3‐c]pyrazoles starting from spirocyclopropanepyrazoles via a ring‐opening/cyanomethylation and intramolecular cyclization is described. Reactions of spirocyclopropanepyrazoles 1a, 1b, 1c, 1d with chloroacetonitrile in the presence of sodium hydride gave the corresponding cyan...

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Bibliographic Details
Published in:Journal of heterocyclic chemistry 2009-07, Vol.46 (4), p.782-787
Main Authors: Maruoka, Hiroshi, Masumoto, Eiichi, Eishima, Takafumi, Okabe, Fumi, Nishida, Sho, Yoshimura, Yuki, Fujioka, Toshihiro, Yamagata, Kenji
Format: Article
Language:English
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Summary:An approach to pyrano[2,3‐c]pyrazoles starting from spirocyclopropanepyrazoles via a ring‐opening/cyanomethylation and intramolecular cyclization is described. Reactions of spirocyclopropanepyrazoles 1a, 1b, 1c, 1d with chloroacetonitrile in the presence of sodium hydride gave the corresponding cyanomethoxypyrazoles 4a, 4b, 4c, 4d. Treatment of 4a, 4b, 4c, 4d with sodium hydride at room temperature caused intramolecular Michael addition reaction to afford the corresponding pyrano[2,3‐c]pyrazoles 5a, 5b, 5c, 5d. J. Heterocyclic Chem., (2009).
ISSN:0022-152X
1943-5193
DOI:10.1002/jhet.117