Stereospecific synthesis of Δ24-sterols labelled on the 26- or 27-methyl group

✍ Scribed by F. Nicotra; F. Ronchetti; G. Russo

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: French
• Weight: 342 KB
• Volume: 14
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.2580140409

✦ Synopsis

Abstract

A convenient synthesis of Δ^24^‐sterols labelled on the 26‐ or 27‐methyl group, exemplified by the synthesis of [26‐^3^H]‐lanosterol, is described. Oxidation of lanosteryl acetate with SeO~2~ gives 3β‐acetoxylanosta‐8, 24‐dien‐26‐al; this is reduced to the corresponding labelled alcohol with KB^3^H~4~ and the obtained hydroxymethyl group is reduced to methyl group by hydrogenolysis of its sulfate monoester. 26‐Hydroxylanosterol can be transformed into 27‐hydroxy lanosterol by E→Z olefin inversion, so allowing the synthesis of lanosterol stereospecifically labelled at C‐27. Desmosteryl acetate analogously affords the corresponding 26‐aldehyde, which is easily reduced to the 26‐alcohol.

^3^H‐stereospecific synthesis.