5,10:13,14-Disecosteroids: novel modified steroids containing 10- and 9-membered rings

Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

“…2, eqn (1)). [24][25][26][27] However, a rationale for the stereoselectivity was not provided in any of these examples. In contrast, direct epoxidation from the b face is reported only in two cases, where an adjacent (homo-allylic) hydroxyl group can direct the stereoselective introduction of oxygen, presumably through hydrogen bonding to the reagent, mCPBA (Fig.…”