Synthese stéréosélective de la phéromone sexuelle “d'aonidiella citrina” le (3S,5E)-(−)-3,9-diméthyle-6-isopropyle déca-5,8-diene-1-yle acétate

Chemistry of the pheromones of mealybug and scale insects

“…In another approach to forming the trisubstituted double bond with excellent (E)-stereoselectivity, reaction of aldehyde 121 (made from (S)-citronellol in a route very similar to that used by Mori, see Scheme 14) with the t-butyl triethylsilylimine 122, prepared in two steps from 5-methylhex-4-enal, followed by elimination of triethylsilanol from the resulting b-hydroxysilane, gave alkenal 123 as an 85 : 15 E/Z mixture (Scheme 17). 56 However, the mixture was readily isomerized to the pure (E)-isomer by treatment with pyridinium hydrochloride in CH 2 Cl 2 . 1,2-Addition of MeMgI to the aldehyde 123, oxidation of the resulting secondary alcohol to the ketone, and Wittig ole-nation gave the conjugated terminal diene 124.…”

Chiral Acylic Synthetic Intermediates from Readily Available Monoterpenoids

“…The alcohol of citronellol has been protected as the acetate 8 or pivaloate ester 9 or as the benzyl 10 11 ethers to permit oxidation of the 6,7-alkene. The alkene has been cleaved by ozonolysis or through the epoxide and reaction with periodic acid to afford the aldehyde 3.…”

“…In some instances, the citronellol or citronellal has been incorporated intact in the syntheses and the isopropyl group has then been removed by ozonolysis to reveal an aldehyde for further modification. Some of the many examples of the use of these compounds in synthesis include muscone, 13 the dolichodials, 14 multistriatin, l7 the Californian red scale insect pheromone, 11 the trigodermols, 20 11,17-dimethyl hentriacontane, 21 4,8-dimethyldecanal, 12 5,9-dimethylpentadecane, 22 the sex pheromone of the German cockroach, 23 6-methyl-2-octadecanone, 24 the sex pheromone of the citrus pest Aondiella citrina, 9 a Puloania bagworm pheromone, 25 and the Phytophthora mating hormone. 26 In several of these examples, the use of the chiral synthon played an important role in establishing the absolute stereochemistry of the bioactive compound.…”