Probing the Active Catalyst in Product-Accelerated Proline-Mediated Reactions.

This article focuses on the active catalyst in proline-mediated reactions. The α-amination and the α-aminoxylation of aldehydes are two recent additions to the rapidly expanding list of proline-based reactions introduced with the discovery of the Hajos-Parrish-Eder-Wiechert-Sauer reaction and elegantly revived by List, with the intermolecular aldol reaction. A key question is whether the low solubility of proline in organic solvents complicates kinetic analyses by including a solid-liquid transport step in the overall observed rate process.