high regio- and diastereoselectivity (>99:1), and excellent enantioselectivity (up to 99%ee). Symmetrical substitution patterns on the aromatic ring of the oxabenzonorbornadienes had no effect on the course of the reaction nor the enantioselectivity. The reaction produces an unusual stereochemical outcome for oxabicyclicringopenings since the trans rather than the cis product is formed. Very low catalyst