Enantioselective Palladium-Catalyzed Oxidative Cascade Cyclization of Aliphatic Alkenyl Amides.

The catalyst system of Pd(TFA)2/(S,S)-diPh-pyrox is reported to promote the highly efficient enantioselective oxidative cascade cyclization of alkene-tethered aliphatic acrylamides under mild aerobic conditions. A series of pyrrolizidine derivatives have been synthesized in good yield and excellent enantioselectivity. Deuterium-labeling experiments have revealed that the reaction proceeded through an anti-aminopalladation (anti-AP) pathway with high selectivity. The transition states for the anti-AP step have been calculated to account for the observed enantioselectivity.