We previously reported an iterative synthesis of unsymmetrical 2,5-disubstituted pyrrolidines from pyrrolidine by two rounds of redox-triggered α-C-H functionalization. Although this approach can be used to introduce substituents at the 2- and 5-positions, it is lengthy because the redox auxiliary must be removed and then reinstalled. Therefore, we sought to develop a method to oxidize 2-functionalized pyrrolidine to cyclic N,O-acetal which could then react with a nucleophile for introduction of the 5-substituent. In this work, we found that molecular iodine can mediate the preferential oxidation of secondary over tertiary α-C-H bonds of α-substituted pyrrolidines to form cyclic N,O-acetals, improving the step economy of our previously reported method. With this strategy, (±)-preussin and its C(3) epimer were synthesized from (±)-pyrrolidin-3-ol.