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3‐Benzoyl‐3,4‐dihydro‐2 H ,5 H ‐1‐benzopyrano[4,3‐ b ]pyran‐5‐ones by condensation of 4‐hydroxycoumarins with enone mannich bases
Author(s) -
Girreser Ulrich,
Heber Dieter,
Schütt Martin
Publication year - 1998
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.5570350640
Subject(s) - chemistry , enone , coumarin , pyran , chromone , double bond , ring (chemistry) , aryl , 4 hydroxycoumarin , stereochemistry , medicinal chemistry , organic chemistry , alkyl , catalysis
Starting from 4‐hydroxycoumarins 4 and 1‐aryl‐2‐(dimethylaminomethyl)prop‐2‐en‐1‐ones 2 the title compounds 6 have been synthesized. The reaction is initiated by addition of the C‐3 carbon atom of 4‐hydroxycoumarin to the enone double bond of the Mannich base, subsequent deamination affords the intermediate 3‐(2‐benzoylallyl)‐4‐hydroxycoumarin 8 , followed by ring closure. Depending on the reaction time, varying proportions of the ketones 6 and 8 are formed and support the mechanism defined. The spectroscopic data of all products unambiguously distinguish between the coumarin and the chromone structures in favor of the former.