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Synthesis of pyrazolo‐fused heterocycles by a tandem appel's dehydration/electrocyclization methodology
Author(s) -
Lee KeeJung,
Kwon HeungTaeck,
Kim BooGeun
Publication year - 1997
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.5570340625
Subject(s) - chemistry , tandem , dehydration , electrocyclic reaction , combinatorial chemistry , organic chemistry , bicyclic molecule , biochemistry , materials science , composite material
Abstract The hydrazones of benzophenone, benzil, and acetophenone were allowed to react with acetoacetanilide to give azinoamides 18 , and the reaction of 18 with Appel's dehydrathon contiditons (triphenylphosphine/carbon tetra‐chloride/triethylatnine) led to the corresponding azinoketimines 19 , which underwent elctrocyclic ring closure under the reaction conditions to give pyrazolo‐fused heterocycles. Azinoamide 18a gave a 4,9‐dihydropyazolo‐[5,1‐ b ]quinazoine 21 , while 18b yielded 2,3‐dihydro‐1 H ‐imidazo[1,2‐ b ]pyrazol‐2‐one 26 and 1 H ‐imidazo[1,2‐ b ]‐pyrazole 29 . Compound 18c gave a monocyclic N ‐α‐styryl‐5‐(phenylamino)pyrazole 32 .