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4‐Diazomethylcoumarins and related stable heteroaryldiazomethanes. Thermal conversion into condensed pyrazoles
Author(s) -
Ito Keiichi,
Maruyama Junko
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.5570250614
Subject(s) - chemistry , substituent , chromone , pyrazolone , thermal stability , pyrazole , alkyl , tricyclic , medicinal chemistry , stereochemistry , organic chemistry
4‐Diazomethyl‐substituted coumarins, 1‐methyl‐2(1 H )‐quinolinones, 1 ‐thiocoumarin and their tricyclic analogs were found to be easily cyclized into the corresponding pyrazole isomers condensed with heteroaromatics. Thermodependent feature of these conversions and the remarkably accelerating effect of the alkyl substituent peri to the diazomethyl group were realized. Some other diazomethyl compounds connected with 2‐pyridinone, 3‐pyrazolone, chromone and 1‐thiochromone were prepared, and their stability and thermal properties were compared.