Soft and weak cooperation: Conformationallyflexible organic compounds were found to promote the title transformation. These “soft” organocatalysts, which are able to control processes through the differential activation entropies (ΔΔS≠S−R) of the reactive intermediates, lead to high stereoselectivities without the requirement of fine‐tuning the reaction temperatures (see scheme).
A bifunctional chiral thiourea―tertiary amine organocatalyst derived from cinchonine was employed to promote the enantioselective Friedel―Craftsalkylation of sesamol and 2-substituted sesamols with various aromatic nitro olefins. The reactions proceeded smoothly to provide the corresponding products in good yields (up to 97 %) and good enantioselectivities (up to 90 % ee).
Herein, we present details of our conformationallyflexible, 1,3‐diamine‐tethered guanidine/bisthioureaorganocatalysts for chemo‐, regio‐, and enantioselective 1,4‐type Friedel–Crafts reactions of phenols. These organocatalysts show a unique stereo‐discrimination governed by the differential activation entropy (ΔΔS≠), rather than by the differential activation enthalpy (ΔΔH≠). Extensive kinetic analyses