Enantioselective Diels-Alder Route to Isoquinuclidines

Significance

An enantioselective catalytic Diels-Alder reaction to isoquinuclidines using a chiral palladium catalyst is reported. Thus, the reaction of a N-protected 1,2-dihydropyridine with acryloyl-1,3-oxazolidine-3-one proceeds under 10 mol% Pd-POZ catalysis in up to 98% yield and with 88% ee. Using 1-benzyl-2-aroylpyrazolidin-3-ones as dienophiles, 87% yield and 97% ee were achieved. Of the several counterions for the Pd-POZ catalyst which were tested, SbF₆ ^- gave the highest ee’s. Other investigated catalysts, such as Cu-bis(oxazoline), Pd-BINAP or other Pd-POZs gave poorer results.