Efficient, stereoselective synthesis of 24(S),25-epoxycholesterol

Efficient, stereoselective syntheses of 24(S),25-epoxycholesterol (1) have been developed starting from cholenic acid (4) or stigmasterol (8), both fe aturing as the key step Sharpless asymmetric dihydroxylation of desmosterol acetate (2). This work permits preparation of gram quantities of 1 for fur ther evaluation as a natural regulator of cholesterol metabolism, specifica lly, e.g., as a ligand for the LXR alpha nuclear receptor.