Synthesis and stability of [3H] 5—demethoxyubiquinone-9

Radioactive [³H]5-demethoxyubiquinone-9 (3-methyl-2-nonaprenyl-6-methoxy-1,4-benzo-quione), an intermediate in the biosynthesis of ubiquione-9 by selected microorganisms and by the rat, has been synthesized. 4-Methyl-3-nitrophenol was converted to the corresponding anisole with [³H]methyl iodide and the anisole was then reduced to the corresponding aniline. Oxidation of 6-methyl-3-methoxy [³H]aniline with chromic acid gave the corresponding 1,4-benzo-quinone which was reduced and alkylated with solanesol in the presence of boron trifluorideetherate. Oxidation with ferric chloride gave two isomers, 5-demethoxyubiquinone-9 and 6-methyl-2-nonaprenyl-3-methoxy-1,4-benzoquinone which were separated by thin layer chromatography. The [³H]methoxyl-5-demethoxyubiquinone-9 prepared had a specific radioactivity of 100 mCi/mmole.