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Synthesis and reactions of halo‐, nitro‐, and arylazo‐substituted 3‐aminotropolones. Formation of 8 H ‐cyclohept[ d ]oxazol‐8‐one derivatives
Author(s) -
Zhang LuoCheng,
Yin BingZhu,
Jin ZhongTian,
Imafuku Kimiaki
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.5570250147
Subject(s) - tropolone , chemistry , bromine , triethyl orthoformate , halogenation , nitric acid , medicinal chemistry , nitro , hydrolysis , nitration , organic chemistry , catalysis , alkyl
3‐Acetamidotropolone ( 1a ) reacted with bromine and fuming nitric acid to afford respectively 3‐acetamido‐7‐bromo‐ ( 1b ) and ‐5,7‐dibromotropolone ( 1c ) and 3‐acetamido‐5‐nitrotropolone ( 1d ). Azo‐coupling reaction of 1a gave 3‐acetamido‐5‐(4‐methylphenylazo)tropolone ( 1f ). Bromination of 1d and 1f gave 7‐bromo‐substituted compounds 1e and 1g , respectively. The compounds 1b‐g were hydrolyzed to afford 3‐aminotropolones 4b‐g , which reacted with triethyl orthoformate to give the corresponding 8 H ‐cyclohept[ d ]oxazol‐8‐ones 5b‐g . Heating of 3‐acetamidotropolones 1a‐d with polyphosphoric acid gave 2‐methyl‐8 H ‐cyclohept[ d ]oxazol‐8‐ones 6a‐d .