Exploring the use of different solvents. Various solvents were evaluated for this transformation, albeit considerable constraints exist in solvent selection with this system to ensure compatibility with the strong bases and solubility of the reaction mixture at low temperatures. Non-polar solvents, for example, are not compatible due to the low solubility of LiBr, which is required to encourage aggregation of the ionic intermediates and good stereoselectivity. To that end, the reaction was attempted using toluene as the solvent in the absence of LiBr, and mostly starting materials (> 85 %, HPLC A %) were observed after the reaction quench. Binary solvent systems containing a non-polar and polar solvent pair were also analyzed (e.g. 1:1 toluene:2-MeTHF, 1:1 hexanes:2-MeTHF, 1:1 DCM:THF) in the presence of LiBr, however, similarly poor conversion was observed, with only trace amounts of products being formed. The replacement of the standard solvent THF with the less polar 2-MeTHF, led to the formation of product albeit at a slower rate of reaction. When the reaction in 2-MeTHF was performed at -78 °C, starting materials 1 and 2 were still the major components of the reaction mixture (Graph 1). This indicates that the reaction in 2-MeTHF is slower than in THF since the retro-addition is not likely at this temperature. When the reaction was carried out at -40 °C, improved conversion was achieved and 72 % of the syn-diastereomer pair, 3 and ent-3, was observed (HPLC A %) along with a 9:1 d.r. (syn:anti). As observed for the reaction in THF at -40 °C, the temperature increase in the 2-MeTHF system also improved enantioselectivity to 55 % ee.