A new monoterpene from Osmanthus fragrans var. thunbergii

In order to study the chemical composition of Osmanthus fragrans var. thunbergii, the chemical constituents of the dried flower of O. fragrans var. thunbergii were studied. From the 95% ethanol extract of the dried flower, a new monoterpene (1), along with seven known monoterpenes, sesquiterpenes and phenethyl alcohols (2-8), was isolated and purified by silica gel, polyamide, and preparative reversed-phase HPLC chromatography methods. Their structures were identified by 1D-NMR (¹H NMR, ¹³C NMR, DEPT), 2D-NMR (HSQC, HMBC, ¹H-¹H COSY, NOESY), HR-ESI-MS, IR, UV, and its physical and chemical properties as:methyl (R,E)-2-(5-ethylidene-2-oxotetrahydro-2H-pyran-4-yl) acrylate (1), (R,E)-2,6-dimethyloct-3,7-dien-2,6-diol (2), (6R)-2,6-dimethyloct-7-en-2,3,6-triol (3), 2,4,4-trimethyl-3-(3-oxobutyl)-cyclohex-2-en-1-one (4), (S)-2,4,4-trimethyl-3-(3-hydroxybutyl)-cyclohex-2-en-1-one (5), (R,E)-2,4,4-trimethyl-3-(3-hydroxybut-1-en-1-yl)-cyclohex-2-en-1-one (6), (S,E)-3,5,5-trimethyl-4-hydroxy-4-(3-oxobut-1-en-1-yl)-cyclohex-2-en-1-one (7), and 2-p-acetoxyphenylethanol (8). 1 is a new compound, 2-8 were isolated from the plant of Osmanthus fragrans var. thunbergii for the first time.