I) CuBr t-BuOOCOPh; II) NaBH4/methanol; III, VI) acetic anhydride, pyridine; IV) CrO3, TBHP, or Co(Ac)2/silica TBHP; V)NaBH4, CeCl3 in 30%THF/methanol; VII) NBS; VIII) r-collidine, xylene. Ec Oxi:Electrochemical Oxidation
Scheme 2: Synthesis endoperoxide 3 from cholesterol.