Understanding the temperature effect. The effect of temperature on the BA reaction with non-chiral bases has been reported previously. It was observed in those studies that carrying out the reaction at temperatures higher than -78 °C strongly favored the retro-addition of the lithium alkoxide 10 leading the reaction equilibrium to favor 1a and 2 (Scheme 6, Equilibrium B). Although the 1,2-addition reaction is reversible, once the temperature is increased other undesired side reactions begin to occur further driving the reaction equilibrium away from the addition adduct 10, even if attempts are made to restore the reaction temperature to -78 °C. It was concluded that the initial lithiation step is also under equilibrium (see Supporting Information/Lithiation mechanism studies section), which follows that as the retro-addition proceeds, the concentration of 1a increases in solution, and the original lithium amide base is reconstituted by the reaction equilibration. Thus, the formation of the enolate 16 begins to disrupt the equilibrium in an irreversible manner since the enolization of 2 is favored at higher temperatures, representing a sink for this reaction.