Substrate‐Dependent Nonlinear Effects in Proline–Thiourea‐Catalyzed Aldol Reactions: Unraveling the Role of the Thiourea Co‐Catalyst

Abstract

It's an affair of four: The study of nonlinear effects in the proline–thiourea-catalyzed aldol reaction between acetone and aromatic aldehydes, together with NMR and ESI-MS experiments, shows that the main role of the thiourea co-catalyst is that of promoting both the formation of a soluble Seebach's oxazolidinone intermediate and its conversion into the iminium carboxylate isomer.