Synthesis and anticancer activity of (R,S)-9-(2,3-dihydro-1,4-benzoxathiin-3-ylmethyl)-9H-purines

A series of eleven 2- and 6-substituted (R,S)-9-(2,3-dihydro-1,4-benzoxathiin-3-ylmethyl)-9H-purine derivatives was obtained by applying a standard Mitsunobu protocol that led to a six-membered ring contraction from (R,S)-3,4-dihydro-2H-1,5-benzoxothiepin-3-ol via an episulfonium intermediate. The signal similar to delta =151 ppm, which corresponds to the C4' carbon atom, is unequivocal proof of the N9' regioisomer. The potential of the target molecules as anticancer agents is reflected in their activity against the MCF-7 cancer cell line. The most active compounds have IC50 values of (6.18 +/- 1.70) and (8.97 +/- 0.83) mu M. The results indicate that the anticancer activity for the most active compounds is correlated with their capacity to induce apoptosis.