Chirality Diels-Alder reaction

The development of chiral Diels-Alder reactions to form enantiomerically enriched isoquinuclidines has been of considerable interest. Older examples focused on the use of chiral auxiliaries, generally attached to the nitrogen of the 1,2-dihydropyridine, the best of which were carbohydrate based <1990TL1995>. Recently, amidines have been shown to be very efficient chiral auxiliaries with l-A-amidine-l,2-dihydropyridine 96 undergoing [4+2] cycloaddition with maleic anhydride to give only the endo-product 97 with >95% diastereomeric excess (Equation 4) <2005OL5773>. 

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