Dry ozonation of steroids. C-25 functionalization of cholestane derivatives Academic Article uri icon

abstract

  • The ozonation of substrates adsorbed on dry silica gel is a convenient method to introduce oxygen into unactivated tertiary CH bonds.'This method involves preadsorption of substrate on chromatographic grade silica gel and passing over it ozone at temperatures between-75 and-45" C, followed by elution with an appropriate solvent. The reactivity of CH bonds toward ozone depends both on the electronegativity of the C atom and on its steric availability. As part of our program to synthesize 25-hydroxycholesterol and its derivatives, we have studied the utilization of ozone as a reagent for the hydroxylation of saturated derivatives of cholesterol as a complimentary method to the previously described* peracetic acid oxidation. We have already publishedId a preliminary report on dry ozonation of ln, 3~- diacetoxy-6, 7-dibromo-5~-cholestane (1 I), which led to C-25 hydroxylation. In this study …

publication date

  • May 1, 2002