Two one-pot procedures starting from diethyl 3,3-diethoxybutyl-phosphanate and aldehydes are proposed for the stereoselective synthesis of the title compounds. In the first one, the use of a Peterson reagent generated in situ, leads to a high (Z)-stereoselective olefination process. In the second, a base-induced 1,2-elimination reaction of a phosphate derivative controls the (E)-stereoselective formation of the double bond.