Synthesis of (-)-albrassitriol and (-)-6-epi-albrassitriol from (+)-larixol.
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-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.
Institute of Chemistry, Academy of Sciences of Moldova, Chisinau, Republic of Moldova. pavel_f_vlad@yahoo.co.uk
Pavel F
PF
Vlad
Alexandru
A
Ciocarlan
Mihai
M
Coltsa
Carolina
C
Edu
Andrei
A
Biriiac
Alic
A
Barba
Calin
C
Deleanu
Alina
A
Nicolescu
Michele
M
D'Ambrosio
Aede
A
de Groot
D060326:Chemistry Techniques, Synthetic; D004224:Diterpenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009284:Naphthols / Q000138:chemical synthesis*; D013237:Stereoisomerism
D004224:Diterpenes; D009284:Naphthols; C433017:labdane; C585511:larixol; C100709:albrassitriol