Synthesis, Spectroscopic Characterization, and Reactivity of Water-Tolerant Eu3+-Based Precatalysts

We report the synthesis, spectroscopic characterization, and reactivity of Eu3+ in the presence of a new set of chiral ligands designed for the aqueous, enantioselective Mukaiyama aldol reaction. Luminescence and NMR measurements were used to characterize the coordination environments of the Eu3+-based precatalysts, and this data is compared with yields and stereoselectivities. In addition to structure–function relationships, we found that, in the presence of excess hexadentate ligands, Eu3+ is coordinatively saturated, and subsequently, the reactivity of the precatalysts is reduced. These findings are helpful for the design of new ligands that bind Eu3+ without saturating the Eu3+ coordination sphere.