Telomerization of Butadiene with Alcohols and Phenol

Primary and short-chained alcohols react very easily with butadiene to form ethers. Hagihara showed that the telomerization of methanol proceeds smoothly even at low temperatures (40—100°C) and with a short reaction time (1—3 h). The primary telomer is always the main product which is accompanied by the secondary telomer and small amounts of the by-product 1,3,7-octatriene. 

A new type of telomerization was found recently by Tkatchenko et aL, when they used cationic palladium complexes as catalysts [11]. Not only methoxyoctadienes were formed by butadiene and methanol, but also Cj2-, Cj6-, C20- and C24-telomers. They presume, that the reaction preferentially occurs via the condensation of Cg-units. 

The telomerization of various higher alcohols has also been carried out. The primary alcohols react most easily with butadiene, whereas secondary and tertiary alcohols yield only small amounts of telomers. Steric hindrance alone cannot be the only factor responsible for the reactivity because the voluminous 2,2-bis(trifluoromethyl)benzylalcohol reacts smoothly to produce the 2,7-octadienyl ether. 

Phenol reacts with butadiene to produce the octadienyl phenyl ethers in high yield [12]. Phenol and butadiene which were heated together at 100 °C in the presence of PdCl2 and PhONa produced trans-1-phenoxyoctadiene in 91% yield which was accompanied by 4% of the d5-isomer and 5% of 3-phenoxy-l,7-octadiene (Equation 11, route A). The condensation of butadiene and phenol, which is carried out in the presence of a tertiary aromatic phosphine or of excess phenol, takes a different course and produces the ortho- and p ra-octadienylphenol (route B). 

The 1-phenoxyoctadiene can be used for the synthesis of 12-acetoxy-l,3-dodecadiene (Equation 12), a pheromone of Diparopsis castanea [13]. In this synthesis, the elimination of the phenol yields the required conjugated diene system. 

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