HIGHLY STEREO- AND REGIOSELECTIVE PALLADIUM-CATALIZED SYNTHESES OF (3E,5Z)-(3E,5E)-,AND (3Z,5E)-1,3,5-UNDECATRIENE

Article abstract of DOI:10.1016/S0040-4020(01)86901-5

(3E,5Z)-1,3,5-Undecatriene (3) having 98.2percent stereoisomeric purity has been prepared by a new and expeditious route involving two selective Pd-catalyzed carbon-carbon bond forming reactions.The key step of this synthesis is a highly diastereoselective Pd-catalyzed cross-coupling reaction between 1-heptynylzinc chloride (11a) and a molar excess of (E)/(Z)-1,2-dibromoethylene (12). Another highly diastereoselective Pd-catalyzed reaction, which involves a cross-coupling between trimethylsilylethynylzinc chloride (15) and molar excesses of stereoisomeric mixtures of 1-bromo-1-alkenes (16), has been used to prepare (E)-1-trimethylsilyl-3-nonen-1-yne (10a), a key intermediate for the synthesis of (3E,5E)- and (3Z,5E)-undecatriene, (4) and (5).Compounds 3 and 4, isolated from the essential oil of Ferula galbaniflua, also occur together with compound 5 in the male attracting oils of seaweeds.These substances have odors highly appreciated in perfumery.