In situ generated aza-π-allylpalladium zwitterions as nucleophilic triggers for enantioselective [4 + 2] cycloaddition with electron-deficient alkenes toward functionalized chiral piperidines

Aza-π-allylpalladium zwitterions, in situ generated from Pd-catalyzed decarboxylation of methylene cyclic carbamates, have so far been reported only as electrophilic triggers for promoting various asymmetric reactions. Herein, for the first time, these zwitterions are used as nucleophilic triggers for the enantioselective [4+2] cycloaddition with electron-deficient alkenes. This reaction provides a facile method to access structurally diverse chiral piperidine derivatives in good yields and enantioselectivities. The utility of this method was demonstrated by a large-scale reaction and product derivatizations.