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Incremental Solvation Precedes Ion-Pair Separation in Enantiomerization of a Cyano-Stabilized Grignard Reagent



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Concerted or stepwise? Ion-pair separation is often proposed as a mechanism for enantiomerization of organolithium reagents in ethereal solvents. But what is the timing of the solvation and bond-cleavage events? Are they concerted, or does one precede the other? Reaction order and Eyring studies of Grignard 1 in Et2O/toluene mixtures clearly demonstrate addition of solvent occurs before rupture of the Mg[BOND]C bond.