A stereoselective synthesis of (.+-.)-nootkatone and (.+-.)-valencene via an intramolecular Sakurai reaction

Anti-allergic activity of sesquiterpenes from the rhizomes of Cyperus rotundus

“…Chemical structures of the tested compounds isolated from the rhizomes of C. rotundus cineole ( Fig. 1), which were identified by comparison of spectral data with published data in the literature (Minyard et al, 1965;Majetich et al, 1985;Miyazawa et al, 1989;Guerrini et al, 2006). Nootkatone was obtained as yellowish needles by Si gel column chromatography with a stepwise elution solvent system (hexane/ethyl acetate = 15:1, 7:1, 3:1, and 1:1) from fraction F7, and identified by comparison with its previously reported spectral data (Miyazawa et al, 2000).…”

Antiplatelet effects of Cyperus rotundus and its component (+)-nootkatone

“…Each of these subfractions was further chromatographed on a silica gel column using a gradient hexane-EtOAc mixture to give valencene (1.03 g, 0.3%), ␤-pinene (0.14 g, 0.04%), limonene (0.20 g, 0.06%), p-cymene (0.07 g, 0.02%) and 1,8-cineole (0.07 g, 0.02%). These five components were identified by comparing their spectral data with published values (Minyard et al, 1965;Majetich et al, 1985;Miyazawa et al, 1989;Guerrini et al, 2006). (+)-Nootkatone (1.6 g, 0.47%) was obtained as yellowish needles by silica gel column chromatography using stepwise elution (hexane:EtOAc = 15:1, 7:1, 3:1, and 1:1, v/v) from another subfraction, and was also identified by comparing its spectral data with previously reported values (Miyazawa et al, 2000).…”

Cydilation of Allyl‐ and Vinylsilanes

“…In contrast, fluoride-catalyzed reactions lead to mixtures of the 1,2 and 1,4 adducts (20) and (21) respectively, as shown in Scheme 6 (cf. With R = CH3 in (18) the sesquiterpene (+)-nootkaton (19) (R = CH3) [23] is obtained in a single step, an example that serves to demonstrate the importance of the Sakurai reaction in terpene chemistry. [14]).…”