Activation of 6-endo over 5-exo epoxide openings. Ring-selective formation of tetrahydropyran systems and stereocontrolled synthesis of the ABC ring framework of brevetoxin B

A new synthetic strategy for the regio- and stereo-specific synthesis of tetrahydropyran systems involving 6-endo epoxide openings and its applicaiton to the construction of the ABC ring system of brevetoxin B are described.