Sesquiterpenes ginseng

An intramolecular photocyclization catalyzed by copper(I) triflate provided a key step in a total synthesis of the ginseng sesquiterpenes a- and /J-panasinsene, (8) and (9). The unsaturated allylic alcohol (6) is cyclized by irradiation at 254 tun in the presence of CuOTf to a mixture of saturated alcohols, which is oxidized to the ketone 7. The ketone is inert to methylenetriphenylphosphorane, but can be converted into a 2 5 mixture of 8 and 9 by addition of mcthyllithium followed by dehydration.2... 

The combination of the chromatographic separation of enan-tiopure p-hydroxysulfoximine diastereomers and reductive elimination results in a method of ketone methylenation with optical resolution. The technique is illustrated in the synthesis of the ginseng sesquiterpene (—)-p-panasinsene and its enantiomer (eq 5). The addition of the enantiopure lithiosulfoximine to prochiral enones or the diastereoface selective addition to racemic enones results in the formation of two diastereomeric adducts. The hydroxy group in these adducts can be used to direct the Simmons-Smith cyclopropanation (eq 6 and eq 7). Catalytic osmylation of such adducts is directed by the anti effect of the hydroxy augmented by chelation by the methylimino group (eq 7). ... 

Panax ginseng C.A. Meyer Ginseng Roots Fatigue and stress, physical performance Ginsenosides, panaxans, sesquiterpenes... 

Ginseng herb oil (P. ginseng) has been reported to contain sesquiterpenes, including bicyclogermacrene, a- and P-panasinsenes, caryophyUene, a- and P-humulenes, a- and P-neoclovenes, P-famesene, and a-, P-, and y-selinenes. ... 

When Chosen ginseng extract was fed to rabbits the urinary output of glucuronic acid was increased in proportion to the dose of the ginseng (321). It was thought that the sesquiterpene of the ginseng probably was decomposed in the body and conjugated with glucuronic acid. 

In a total synthesis of the ginseng sesquiterpene (—)-j8-panasinsene, ketone methylenation with optical resolution was reported [12a]. Thus, a kinetic resolution was operative in the reaction of the lithium carbanion of chiral sulfoximide 201 with the racemic ketone 200, giving a separable mixture of two compounds, (+)-202 and (+)-203. The latter diastereomer was converted to the natural product. 

---