Scheme 2. Mapping the fate of the stereocentres when using different reaction conditions. Reaction conditions: A: 1.3 equiv. sBuLi, Et2O (0.3 M), –78 °C, 1 h; 1.5 equiv. boronic ester in Et2O (1.0 M), –78 °C, 2 h; –78 °C → r.t., o/n; B: 1.3 equiv. sBuLi, Et2O (0.3 M), –78 °C, 1 h; 1.5 equiv. boronic ester in Et2O (1.0 M); 1.3 equiv. of MgBr2 in MeOH (1.0 M), then –78 °C → r.t., o/n.
