Patent ID: 7271296

Claim:
A process for preparing phytofluene of the formula I, which comprises a) condensing a phosphonium salt of the formula II, in which R 1 is aryl and X − is the anion equivalent of an inorganic or organic acid, with an aldehyde of the formula III in a Wittig reaction to give an acetal of the formula IV where the substituents R 2 and R 3 are independently of one another C 1 —C 8 -alkyl, or together with the oxygen atom and the carbon atom to which they are bonded may form a 1,3-dioxolane or 1,3-dioxane ring of the following structures in which R 4 and R 5 , and R 6 may each independently of one another be hydrogen or C 1 —C 4 -alkyl, b) subjecting the condensation product of the formula IV to an acid-catalyzed acetal hydrolysis to give the aldehyde of the formula V c) and condensing V in a further Wittig reaction with a phosphonium salt of the formula VI, in which R 7 is aryl and Y − is the anion equivalent of an inorganic or organic acid, to give phytofluene.