Constraining titanium tartrate in the interlayer space of layered double hydroxides induces enantioselectivity

Kagan-Medona and Sharpless titanium tartrate complexes (Ti(IV)TAm, subscript m represents the coordination ratio of l-tartaric acid to the Ti center in the complex) have been intercalated into the interlayer of layered double hydroxides (LDHs) by anionic exchange method using Mg/Al–CO3 LDH as the precursor. Titanium tartrate-intercalated LDHs (designated Mg/Al–Ti(IV)TAm LDHs) with varied interlayer spacing were produced by tuning the area unit charge (Ac) of the brucite-like layer from 0.24 to 0.44 nm2. The interlayer spacing decreases from 1.87 to 1.44 nm with the increase in Ac. The interlayer titanium tartrate anions are present in an interdigitated bilayer arrangement. The bidimensional interlayer space can be swollen, and thus accommodates the reactants in the interlayer. The titanium tartrate complex constrained in the LDH interlayer region shows enhanced asymmetric induction in the heterogeneous sulfoxidation of pro-chiral methyl phenyl sulfide.