Syntheses of a prenylbisabolane diterpene, a natural insecticide from Croton linearis, and of the bisabolane sesquiterpenes (-)-delobanone and (-)-epi-delobanone

• An enantioselective first total synthesis of a constituent of Croton linearis, the (-)-7-hydroxy-3,10-prenylbisaboladien-2-one 1, is described as well as the syntheses of the 7-hydroxy-3,10-bisaboladien-2-ones (-)-epi-delobanone (14a) and (-)-delobanone (14b). The model compounds, 7-hydroxy-11-nor-methyl-3-bisabolen-2-one (8a), and 11,15-nor-dimethyl-7-hydroxy-3-bisabolen-2-one (8b), were successfully prepared by opening of the protected carvone epoxide derivative 6 with the appropriate organocuprates. An alternative approach was used for compounds 1 and 14. Thus, these were obtained from homogeranyllithium or homoprenyl Grignard reagent, which reacted successfully with a masked nor-carvone, ketone 11, prepared in four steps from (R)-carvone.

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NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Carvone enantioselctive synthesis Bisabolane

Chemistry

Kemi

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