Synthesis of (2E,6E)‐[10‐3H]farnesol and (2E6E)‐[10‐3H]farnesal for insect dehydrogenase studies

Abstract

Abstract[10‐3H]Farnesol ((2E,6E)‐3,7,11‐trimethyl‐2,6,10‐dodecatrien‐1‐ol) and [10‐3H]farnesal ((2E,6E)‐3,7,11‐trimethyl‐2,6,10‐dodecatrien‐1‐al) were synthesized by sequential reduction and oxidation of the corresponding tert‐butyldiphenylsilyl protected 11,12,13‐trisnoraldehyde, followed by Wittig homologation using isopropyltriphenylphosphorane. Direct reduction of the C‐12 allylic bromide or allylic chloride proved to be an nonviable method, resulting in either multiple decomposition products or significant double bond transposition. Oxidation of the [10‐3H]labelled trisnoralcohol with pyridinium chlorochromate resulted in essentially complete retention of the radiolabel as was established for the corresponding deuterated material. [3H]labelled farnesol and farnesal were obtained in 78% and 74% yields, respectively, from the trisnoraldehyde. These materials were used as radiotracers for examining the enzymatic activity of insect farnesol and farnesal dehydrogenase, key enzymes in the biosynthesis of juvenile hormone.