Аннтотация

The [4+2] cycloaddition of chromone-fused dienes with enamines is an efficient method of synthesis of 4,4a- and 3,4-dihydroxanthone derivatives. Either product type can be obtained by choosing the proper conditions (reaction time and addition of La(NO3)3 as Lewis acid). Calculations using density functional theory and Møller-Plesset perturbation theory show that the isomerization of 4,4a-dihydroxanthones to 3,4-dihydroxanthones occurs as a base-assisted sigmatropic rearrangement. The described reaction provides a convenient route to a natural product inspired group of 4,4a-dihydroxanthones with cytotoxic activity.