Stereochemistry in dehydrogenation of 3α, 7α, 12α-trihydroxy-5β-cholestan-26-oyl CoA during cholic acid biosynthesis

Abstract

The dehydrogenation reaction, catalysed by 3a, 7a, 12a-trihydroxy-5~-cholestan-26-oyl CoA oxidase, is elucidated to proceed via syn-elimination of [24-pro-R]-hydrogen and 25-hydrogen.

Steroids: reactions and partial synthesis

“…The stereochemistry of the biosynthetic addition of hydrogen to C-25 of desmosterol has been e~tablishedl~~ using[26-13C]-and [27-13C]-labelled desmosterol. The key step in the preparation of the [27-13C]-2abelled desmosterol was a Wittig reaction between the aldehyde(135) and the phosphonium salt(136) which gave the (24E) isomer(137) as the major product.…”