Solvation of the Carbonyl Compound as a Predominant Factor in the Diastereofacial Selectivity of Nucleophilic Addition.

Temperature-dependent selectivity in nucleophilic additions is affected by the solvent. The inversion temperature (marked with arrows in the graph) that appears in the nonlinear Eyring plots of ln (anti/syn) versus temperature for the addition of butyllithium to an O-protected α-hydroxy aldehyde 1 does not depend on nucleophiles (nBuLi (▴), tBuLi (•)), but on the solvent. Its value can be obtained from a plot of the 13C NMR chemical shift of C=O versus temperature. TBDMS=tBuMe2Si.