Structure Identification: |
Nat Prod Res. 2013;27(9):809-17. | Synthesis of (-)-albrassitriol and (-)-6-epi-albrassitriol from (+)-larixol.[Pubmed: 22794273 ] | A novel synthesis of natural drimanic compounds, (-)-albrassitriol (2) and (-)-6-epi-Albrassitriol (3), has been carried out starting from an easily available labdane diterpenoid, (+)-larixol (1).
METHODS AND RESULTS:
In a two-step procedure, (+)-larixol (1) was converted into 14,15-bisnorlab-7-ene-6,13-dione (9), which was then submitted to a Norrish type II photochemical degradation yielding drim-7,9(11)-diene-6-one (10), whose treatment with OsO4 led selectively to the formation of drim-7-ene-9α,11-diol-6-one (12). The same compound was obtained by selective epoxidation of the C(9)-C(11) double bond in drim-7,9(11)-diene-6-one (10) with monoperphtalic acid.
Treatment of the resulting mixture of α- and β-epoxides (13 and 14) with HClO4 yielded drim-7-ene-9α,11-diol-6-one (12). Reduction of the C6-carbonyl group in drim-7-ene-9α,11-diol-6-one (12) with LiAlH4 afforded (-)-albrassitriol (2) and (-)-6-epi-Albrassitriol (3), 12.4% and 13.6% overall yields, respectively. |
|