Efficient Total Synthesis of Piceatannol via (E)-Selective Wittig-Horner Reaction

Efficient and practical total synthesis of piceatannol via (E)-selective Wittig-Horner reaction is demonstrated with six steps in overall 40% yield from a commercially available, cheap starting material, 3,5-dihydroxybenzoic acid. Wittig-Horner reaction of diethyl phosphonate with aldehyde showed a superior (E)-selectivity compare to Wittig reaction using triphenylphosphine. We optimized the Wittig-Horner reaction condition by using NaH (6 equiv) in tetrahydrofuran (THF) at reflux 1h to give 99% yield of single (E)-stilbene.