A number of α-methyl-furano-flavones and their dihydro derivatives have been prepared using 7-hydroxy-8-allyl flavone derivatives. Ring closure is effected with anhydrous hydrogen bromide followed by pyridine and dehydrogenation with N-bromosuccinimide. 2-Methyl cromone derivatives have also been made. Tests with fish of select compounds indicate that dihydrofurano compounds are better poisons and an α-methyl group reduces toxicity in the furano compounds.

The effect of chelation on the carbonyl frequency of xanthones is to lower it just as in the case of flavanones, isoflavanones and simpler ketones. This supports the explanation given earlier regarding the special behaviour of flavones and isoflavones. Benzophenones and anthraquinones resemble xanthones in this respect.