Enantioselective catalytic desymmetrization of maleimides by temporary removal of an internal mirror plane and stereoablative over-reduction: synthesis of (R)-pyrrolam A.

A highly enantioselective (>95% ee) strategy to affect the desymmetrization of a maleimide has been performed by temporary attachment to an anthracene template followed by asymmetric reduction with an oxazaborolidine catalyst. A stereoablative over-reduction process was partially responsible for the high levels of enantioselectivity. Exemplification of the strategy by stereoselective functionalization and retro-Diels-Alder reaction provided the natural product pyrrolam A.