SYNTHESIS OF ETHYL 3,7,11-TRIMETHYL-2,4-DODECADIENOATE (HYDROPRENE) FROM 4-METHYLTETRAHYDROPYRAN

Article abstract of DOI:10.1007/BF00956974

A new pathway has been proposed for the synthesis of the ethyl ester of 3,7,11-trimethyl-2,4-dodecadienoate (juvenoid hydroprene) from available 4-methyltetrahydropyran.The cleavage of the latter to 3-methyl-5-bromo-1-acetoxypentane and coupling with isobutylmagnesium bromide gave tetrahydrogeraniol, which was oxidized to the corresponding aldehyde.The reaction of this aldehyde with allylmagnesium chloride and subsequent oxidation by O2/PdCl2-CuCl led to 6,10-dimethyl-3E-undecen-2-one, which was converted by a known method to the desired product as a mixture of 70 percent 2E,4E- and 30 percent 2Z,4E-stereoisomers.The yield of hydroprene in the six-step synthesis was 32 percent relative to 4-methyltetrahydropyran.