93290-61-0Relevant academic research and scientific papers
Synthesis of novel C-methylflavones
Hauteville, Marcelle,Gaillard, Pascale,Kaouadji, Mourad,Duclos, Marie-Christine
, p. 1217 - 1222 (2007/10/03)
If the Baker-Venkataraman rearrangement of C-methylphloracetophenone triaroyl esters is carried out in DMSO with powdered NaOH, the result greatly depends on the substitution pattern both of the phloracetophenone moiety possessing either one or two C-methyl groups and of the aroyl parts bearing a conjugated methoxy group (or not such a group) with respect to the carbonyl group. With benzoyl, 4-methoxybenzoyl or 3,4-dimethoxybenzoyl as aroyl group the 3,5-dimethylphloracetophenone triaroyl esters 10a-c directly yield the corresponding unsubstituted ring B or 4′-methoxy- and 3′,4′-dimethoxy-substituted 5,7-dihydroxy-6,8-dimethylflavones 11a-c. In contrast, the 3-methylphloracetophenone triaroyl esters 3a-c react quite differently, depending on the aroyl substitution pattern. Thus, the triester 3a containing benzoyl groups gives the hemiketal Wessely-Moser isomers 5a, 5a′ whereas the triesters 3b and 3c containing 4-methoxy- or 3,4-dimethoxybenzoyl groups are converted into compounds existing as two equilibria of two β-diketo and two β-keto enol tautomers. Finally, dehydration of each mixture furnishes solely the corresponding unsubstituted ring B or 4′-methoxy- and 3′,4′-dimethoxy-substituted 5,7-dihydroxy-6-methylflavones 8a-c. Methylation of 11c affords 7-O-methyl and 5,7-di-O-methyl derivatives 12a and b. VCH Verlagsgesellschaft mbH, 1996.
