Farnesene allylation

PALLADIUM-CATALYZED SYNTHESIS OF 1.4-DIENES BY ALLYLATION OF ALKENYLALANES a-FARNESENE... 

PALLADIUM-CATALYZED SYNTHESIS OF 1,4-DIENES BY ALLYLATION OF AUENYLALANES a-FARNESENE (1,3,6,10-Dodecatetraene, 3,7,11-trlmethyl-)... 

From the oil of Santalum spicatum (R.Br.) A.DC., Birch et al have isolated the two isomeric dihydrofarnesenes (1) and (2). These two compounds, although not identical with the trail pheromone of the Nasutitermes species of termites, both exhibit similar specific trail activities. Cavill and Coggiola have reported that the photosensitized oxygenation of a-farnesene (3) yields the five allylic alcohols (4)—(8) after reduction of the corresponding hydroperoxides. A new... 

Application of the Pd-catalyzed alkenyl-allyl coupling to totally regio- and stereo-controlled synthesis of a-farnesene [92] and a recent synthesis of coenzymes Q3 and Q5 via Ni-catalyzed alkenyl-benzyl coupling [103] demonstrate the synthetic utility of this novel allylation and benzylation methodology (Schemes 1-29 and 1-30). 

An example of a palladium-catalyzed stereospecific and regioselective coupling of an allylic chloride with an alkenylalane derived via Zr-catalyzed methylalumina-tion in the synthesis of a-farnesene is shown below. ... 

Dienic carboxylic acids. Prater has described a method for addition of an isoprene unit to an allylic alcohol. The method is iUustrated for the conversion of the ester (1) of geraniol into farnesenic acid (3). The ester is treated with lithium N-isopropylcyclohexylamide (LilCA, 4, 306-309) and then with trimethylchlorosilane. The resulting trimethylsilylketene acetal (a) undergoes... 

Sinensal (18) and /3-farnesene (19) have both been synthesized from the thioncarbamate (16), which undergoes a [3,3] sigmatropic rearrangement to produce the allylic thiolcarbamate (17) (Scheme 1)/ The Grignard reagent... 

Fig. 6.7 A case of moonlighting. The S. coelicolor CYP170A1 converts epi-isozizaene via albaflavenol intermediate(s) to the sesquiterpene single ketone antibiotic albaflavenone by two successive allylic oxidations (a) [202], A secondary terpenoid synthase role was also discovered to produce farnesene (b) [849]. The structure...

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