Solvent- or Temperature-Controlled Diastereoselective Aldol Reaction of Methyl Phenylacetate

Unlike the enolboration–aldolization of methyl propanoate, the choice of either the solvent or temperature determines the diastereoselectivity during the enolboration–aldolization of methyl phenylacetate. In CH₂Cl₂, the reaction favors the anti-pathway at −78 °C and the syn-pathway at rt. Conversely, the reaction produces the anti-isomer up to rt and the syn-isomer at refluxing temperatures in nonpolar solvents.