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Selective instability of trifluoromethyl linked to carbon. A prerequisite for new heterocyclizations with ethyl 4,4,4‐trifluoroacetoacetate arylhydrazones
Author(s) -
Pilgram Kurt H.,
Skiles Richard D.
Publication year - 1988
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.5570250120
Subject(s) - chemistry , sodium hydride , trifluoromethyl , sodium ethoxide , deprotonation , sodium fluoride , fluoride , ethanol , medicinal chemistry , hydride , bicyclic molecule , sodium , ion , organic chemistry , inorganic chemistry , hydrogen , alkyl
Highly functionalized pyrazoles, 2 , and 1 H ‐pyrazolo[3,4‐ d ]pyridazinones 3 have been obtained in moderate yields from ethyl 4,4,4‐trifluoroacetoacetate o ‐chlorophenylhydrazones 1 by treatment with sodium hydride in aprotic solvents. Treatment of 2 and 3 with sodium ethoxide in ethanol gave bicyclic 5‐(5‐oxopyrazol‐3‐yl)‐pyrazolones 4 and 5 in high yields. The reactions of 1 with sodium hydride which are accompanied by the loss of fluoride ion from one trifluoromethyl group implicate the anchimeric assistance of an N ‐deprotonated anion of 1 in the initial reaction step.