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). 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-9,11-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 - and -epoxides (13 and 14) with HClO4 yielded drim-7-ene-9,11-diol-6-one (12). Reduction of the C6-carbonyl group in drim-7-ene-9,11-diol-6-one (12) with LiAlH4 afforded ()-albrassitriol (2) and ()-6-epi-albrassitriol (3), 12.4% and 13.6% overall yields, respectively.
- drimane sesquiterpenoids
Vlad, P. F., Ciocarlan, A., Coltsa, M., Edu, C., Biriiac, A., Barba, A., Deleanu, C., Nicolescu, A., D'Ambrosio, M., & de Groot, Æ. (2013). Synthesis of ()-albrassitriol and ()-6-epi-albrassitriol from (+)-larixol. Natural Product Research, 27(9), 809-817. https://doi.org/10.1080/14786419.2012.706297