Abstract: An improved process for the preparation of polyenes by the Julia reaction comprises carrying out the allylation of the anion of an allyl aryl sulfone generated a strong base, and the elimination of arylsulfinic acid to form a double bond in the same inert polar solvent which is immiscible with water, preferably in a ketone of the formula IR.sup.1 --CO--R.sup.2 (I)where R.sup.1 and R.sup.2 are each straight-chain or branched alkyl of 2 to 4 carbons, or R.sup.1 and R.sup.2 together are tetramethylene or pentamethylene. The process is particularly important for the preparation of vitamin A derivatives. In the preparation of vitamin A aldehyde, for example, it is advantageous to use the same alkali metal alcoholate as strong base in both stages so that the conversion can be carried out as one-pot reaction.