Sequential enantiodivergent organocatalysis: reversibility in enantioswitching controlled by a conformationally flexible guanidine/bisthiourea organocatalyst
Here we describe our studies on solvent-dependentenantiodivergentMannich-typereactionsutilizingconformationallyflexibleguanidine/bisthioureaorganocatalyst (S,S)-1. Our mechanistic investigations revealed that the stereo-determining steps in both the (R)- and (S)-selective Mannich-typereactions are governed by the cooperative effect of guanidine and thiourea in the inherently monomeric structure