Approaches to 2-substituted chroman-4-ones: synthesis of (−)-pinostrobin

Two approaches to optically active 2-substituted chroman-4-ones are described. The first utilized the oxidation of a preformed chroman ring and the second an intramolecular Mitsunobu cyclization. The methodology was applied to the synthesis of the biologically active natural product (−)-pinostrobin (18).