Inter- and intramolecular Mitsunobu reaction based approaches to 2-substituted chromans and chroman-4-ones

Two approaches to optically active 2-substituted chromans and chroman-4-ones are described. The first utilized an intermolecular Mitsunobu reaction of a homochiral halopropanol and 2-bromophenol followed by cyclization to the 2-substituted chroman. In addition, a double lithiation procedure was developed to introduce additional functionality to the chroman. The second approach utilized an intramolecular Mitsunobu cyclization to give the 2-substituted chroman-4-one nucleus. The methodologies were applied to the syntheses of several biologically active natural and synthetic products.