Synthesis of α, α-Dimethyl-β-ethylallenolic Acid and 6-Methylthio-α, α-dimethyl-β-ethyl-2-naphthalenepropionic Acid

Condensation of 6-methoxy- and 6-methylthio-2-propionaphthone with t-butyl α-bromoisobutyrate gave the corresponding t-butyl β-hydroxy esters in yields of 80 and 84% respectively. The treatment of the β-hydroxy esters with iodine in the presence of red phosphorus in boiling acetic acid effected reductive cleavage to produce 6-hydroxy- and 6-methylthio-α, α-dimethyl-β-ethyl-2 naphthalenepropionic acid in yields of 33 and 34% respectively. Reduction of the former ester in the presence of palladium-charcoal in acetic acid gave α, α-dimethyl-β-ethyl-6-methoxy-2-naphthalenepropionic acid in a 49% yield.