N, N′-Bis[3,5-bis(trifluoromethyl)phenyl]thiourea: a privileged motif for catalyst development

Over the last decade, the use of (thio) urea derivatives as organocatalysts in organic chemistry has increased rapidly. One of the key features is their ability to activate substrates and subsequently stabilize partially developing negative charges (e. g., oxyanions) in the transition states employing explicit double hydrogen bonding. Among (thio) urea-based catalysts, N, N'-bis[3,5-bis(trifluoromethyl)phenyl]thiourea developed by Schreiner's group (abbreviated here as Schreiner's thiourea) has played a very important role in the development of H-bond organocatalysts. Nowadays it is used extensively in promoting organic transformations, and the 3,5-bis(trifluoromethyl) phenyl motif thereof is used ubiquitously in H-bond catalysts. This review summarizes the key developments of Schreiner's thiourea-mediated reactions with the aim to further expand the applications of (thio) urea-based catalysts.