Different ratios of a binary mixture of 2-MeTHF:THF were also screened at -40 °C (Graph 2). The addition of a small amount of THF (25 %) to 2-MeTHF (3:1 2-MeTHF:THF) was enough to reduce the syndiastereomer pair (3 and ent-3) amount by more than half, from 72 % to 30 % (HPLC A %). The higher the THF percentage in this binary mixture, the more the equilibrium favors the retro-addition and enolization of 2. The use of 2-MeTHF alone was found to provide superior conversion of starting materials. This result was considered to be very promising, as performing the BA reaction at increased temperature would offer practical improvement to throughput due to the enhanced enantioselectivity towards BDQ (3) as well as ease operational issues of cryogenic reactions for manufacturers.