By a Wittig condensation of 5,9-dimethyl-4,8-decadien-1-yltriphenylphosphonium iodide (I) with 4-methyl-6-tetrahydropyranyloxy-4-hexenal (II) using butyllithium as condensing agent in THF, followed by reaction with paraformaldehyde and sec-butyl lithiurn in the same solvent.
The condensation of genanyl bromide (VIII) with methyl 4,4-dimethoxyacetylacetate (IX) by means of sodium ethoxide in refluxing ethanol gives 1,1-dimethoxy-6,10-dimethyl-5,9-undecadiene-2-one (X), which is submitted to a Wittig condensation with (4-methyl-6-tetrahydropyranyloxy-4-hexenyl)triphenyl phosphonium iodide by means of n-butyllithium in hexane yielding 7-formyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol (XII). Finally, this compound is reduced with NaBH4 in ethanol.
The condensation of homogeranyl iodide (III) with diethyl ethoxycarbony-methylphosphonate (IV) by means of NaH in diethoxyethane gives the phosphorane (V), which by a Wittig condensation with 4-methyl-6-acetoxy-4-hexenal (VI) by means of NaH yields 7-(ethoxycarbonyl)-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol acetate (VII). Finally, this compound is reduced and hydrolyzed by treatment with LiAlH4.