Synthesis of benzopyran prostaglandins,potent stable prostacyclin analogs,via an intramolecular mitsunobu reaction

Short syntheses of the extremely potent benzopyran prostacyclin mimics 26 and 27 are described using a novel intramolecular Mitsunobu reaction (e.g. 20 → 22) in the key step. This mild cyclization method was also applied to the synthesis of some simple chromans and benzofurans (34 – 38).