Treatment of hydroxy-2,2-dimethyl chromans1,4,8 with ethyl acetoacetate (EAA) in the absence of any condensing agents afforded a mixture of dihydropyrano coumarins and dihydropyrano chromones,2+3,5+6 and9+10 respectively. Demethylation of methyl ethers of dihydro-spatheliachromene (6) and-alloptaeroxylin (10) using anhydrous AlCl3-CH3CN yielded the correspond chromans,7 and11.
Volume 134, 2022
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