A general approach to synthesis of labeled brassinosteroids: Preparation of [25,26,27-2h7]brassinolide with 60% isotopic purity from the parent brassinolide

Article abstract of DOI:10.1016/S0040-4039(98)01636-0

From brassinolide (BL) 1, [25,26,27-²H(n)]BL 10 was synthesized in 5 steps including C-25 hydroxylation, dehydration and catalytic deuteriogenation. In direct oxy-functionalization of tetra-O-acetyl BL 2 with methyl(trifluoromethyl)dioxirane leading to 25-hydroxyl compound 3, 14- hydroxyl, 25-hydroxy-15-oxo and 14,25-dihydroxyl derivatives, 4, 5 and 6, were newly identified; the catalytic deuteriogenation of Δ(25(26))-BL 8 using 5% palladium-on-charcoal resulted in abundant incorporation of deuterium atoms to give 10 with 60% isotopic purity of [25,26,27-²H₇]BL.