Biosynthesis of poriferasterol in Ochromonas malhamensis: 13C NMR assignment of the isopropyl methyl groups of 2-methylpentan-3-ol

2-Methylpentan-3-ol stereospecifically labelled with deuterium on one of the isopropyl methyl groups has been synthesized, thus allowing the unequivocal assignment of their 13C NMR resonances. 13C NMR assignments for these groups proposed earlier are shown to be incorrect. Involvement in the biosynthesis of the 24β-ethylsterol poriferasterol in the crysophyte Ochromonas malhamensis is discussed.