Syntheses and activities of sulfur and selenium isosteric substitution analogs of retinol

The syntheses of sulfur and selenium isosteric substitution analogues of retinol, namely, retinyl phenyl thioether (2b), retinyl phenyl selenoether (2c), and retinyl thioacetate (2e) are described. These retinoid derivatives were examined for activity in terms of "chemoprevention" of cancer by measuring the reverse keratinization of epithelial cells in vitro. Retinoid analogues 2b, 2c, and 2e were found to be active in 20, 80, and 33.3% of the cultures, respectively, as compared to 72.7% activity for trans-retinol.