| abstract |
The dibenzopyranones of formula III are prepared by condensation of a 4-(hydroxymethylene)chromanone of formula IV with methyl vinyl ketone. The substances of formula IV can be obtained by introduction of the hydroxymethylene substituent at position 3 by reaction of the corresponding compound not carrying this substituent with ethyl formate in the presence of sodium hydride. The compounds of formula III are particularly useful as intermediates in the synthesis of medicaments. <IMAGE>n[CH622790A5] |