5-Phenyl-2,4-pentadienyl acetate

It is known that tr-allylpalladium acetate is converted into allyl acetate by reductive elimination when it is treated with CO[242,243]. For this reason, the carbonylation of allylic acetates themselves is difficult. The allylic acetate 386 is carbonylated in the presence of NaBr (20-50 mol%) under severe conditions, probably via allylic bromides[244]. However, the carbonylation of 5-phenyl-2,4-pentadienyl acetate (387) was carried out in the presence of EtiN without using NaBr at 100 °C to yield methyl 6-phenyl-3,5-hexadienoate (388)[245J. The dicarbonylation of l,4-diacetoxy-2-butene to form the 3-hexenedioate also proceeds by using tetrabutylphosphonium chloride as a ligand in 49% yield[246]. 

Carbonylation of the 3-phenylallyl acetate 258 under somewhat severe conditions in the presence of tertiary amine and acetic anhydride affords the naphthyl acetate derivative 260. This interesting cyclocarbonylation is explained by the Friedel-Crafts-type cyclization of the acylpalladium 259 as an intermediate [118,119]. Even 5-phenyl-2,4-pentadienyl acetate (261) is cyclocarbonylated to afford 2-phenylphenyl acetate (262) [120],... 

A versatile method for the preparation of allyl complexes of transition elements involves addition of allyl halides or acetates to low oxidation state coordinatively unsaturated, or potentially unsaturated, complexes (214). A few attempts have been made to extend the method to halogenopentadienes. l-Chloro-5-phenyl-2,4-pentadiene adds to Pd2(dba)3 (dba = dibenzoylac-etone) to give the >/3-pentadienyl complex 61 [Eq. (30)] (215). A similar palladium complex has also been obtained from PdCl2, and 2,5-dimethyl-2,4-hexadiene in isopropanol (216). 

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