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The chemistry of 2 H ‐3,1‐benzoxazine‐2,4(1 H )‐dione (isatoic anhydride). 21 . a mild process for the preparation of 10‐alkyl‐9‐acridanones and it's application to the synthesis of acridone alkaloids
Author(s) -
Coppola Gary M.,
Schuster Herbert F.
Publication year - 1989
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.5570260414
Subject(s) - chemistry , acridone , organic chemistry , alkyl , lithium (medication) , palladium , medicinal chemistry , catalysis , endocrinology , medicine
10‐Substituted‐9‐acridanones are readily prepared by the reaction of the corresponding isatoic anhydride with the lithium enolate of 2‐cyclohexen‐1‐one. The initially formed product, the 1,2‐dihydroacridone need not be purified but can be aromatized directly with DDQ to the desired acridone. This methodology is applicable to the synthesis of acridone natural products. Two alkaloids, 1,2,3‐trimethoxy‐10‐methylacridone ( 9 ) and evoxanthine ( 10 ), were prepared from 4,5,6‐trimethoxy‐ N ‐methylisatoic anhydride and 6‐methoxy‐4,5‐methyl‐enedioxy‐ N ‐methylisatoic anhydride respectively. In these trioxygenated systems, palladium‐on‐charcoal must be used to aromatize the penultimate intermediate.