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Ring transformation of spirocyclopropanepyrazoles into pyrano[2,3‐ c ]pyrazoles
Author(s) -
Maruoka Hiroshi,
Masumoto Eiichi,
Eishima Takafumi,
Okabe Fumi,
Nishida Sho,
Yoshimura Yuki,
Fujioka Toshihiro,
Yamagata Kenji
Publication year - 2009
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.117
Subject(s) - chemistry , sodium hydride , intramolecular force , ring (chemistry) , hydride , medicinal chemistry , michael reaction , pyrazole , transformation (genetics) , stereochemistry , organic chemistry , catalysis , hydrogen , biochemistry , gene
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).