An aza-Prins cyclization approach to functionalized indolizidines from 2-allylpyrrolidines.

The stereoselective synthesis of a diverse set of functionalized indolizidine systems has been accomplished through the aza-Prins cyclization of 2-allylpyrrolidines. The condensation of aldehydes onto 2-allylpyrrolidines yields iminium ions that undergo highly diastereoselective aza-Prins cyclization, producing up to two stereogenic centers and two new rings in one step.