Treatment of hydroxy-2,2-dimethyl chromans
1,
4,
8 with ethyl acetoacetate (EAA) in the absence of any condensing agents afforded a mixture of dihydropyrano coumarins and dihydropyrano
chromones,
2+
3,
5+
6 and
9+
10 respectively. Demethylation of methyl ethers of dihydro-spatheliachromene (
6) and-alloptaeroxylin (
10) using anhydrous AlCl
3-CH
3CN yielded the correspond chromans,
7 and
11.
Keywords 2,2-Dimethyl-2H-pyrano-coumarins and -chromones - ethyl acetoacetate - condensation