Thermal stability of 7-trimethylsilylperoxy-cholest-5-ene 3 beta-acetates at high temperature

The thermal degradation of the two hydroperoxy isomers (7 alpha- and 7 beta -hydroperoxides) of cholest-5-ene3 beta -acetate (CA) generates many produ cts, of which most have already been identified; the two 7-hydroxy-CA alpha - and beta -isomers are among these compounds. In the case of the 7 alpha - hydroperoxy-CA degradation. the isomer 7 alpha -hydroxy-CA is present in a high proportion, while the 7 beta -isomer is generated in a larger amount f rom the 7 beta -hydroperoxy-CA. The thermal degradation of the trimethylsil yl derivatives (TMS) of the 7-hydroperoxy-CA gives rise to many products, o f which several components are the same as those obtained from the correspo nding non silylated 7-hydroperoxy-CA isomer. We have found an unexpectedly high amount of the TMS derivative of the 7-hydroperoxy-CA (7 alpha- or 7 be ta -isomers). Traces of free 7 alpha -hydroperoxy-CA, from thermal degradation of each 7- hydroperoxide-CA TMS (7 alpha- and 7 beta- isomers), were also found.