Scheme 5. Scale-up reaction and derivatisation of allylated product 3aa.a aReaction conditions: (i) 1 (2.5 mmol, 1.0 equiv.), 2a (2.8 mmol, 1.1 equiv.), [Pd(π-C3H5)Cl]2 (2.5 mol%), L1 (7.5 mol%), CH2Cl2, rt, 1 h. Yield determined by 1H NMR integration against an internal standard (dimethyl sulfone), isolated yield in parentheses. (ii) 3aa (1.0 equiv.), NaBH4 (4.5 equiv.), MeOH, 0 °C, 1 h. (iii) Boc2O (1.3 equiv.), DMAP (0.4 equiv.), CH2Cl2, rt, overnight. (iv) (a) 3aa (1.0 equiv.), K-Selectride® (2.2 equiv.), THF, −10 °C, 1 h. (b) Boc2O (2.3 equiv.), DMAP (14 mol%), −10 °C to rt, overnight. (v) LiAlH4 (3.1 equiv.), THF, reflux, 1.5 h. Isolated yield. Diastereomeric ratio determined from the 1H NMR spectrum of the crude reaction mixture. bMinor diastereoisomer also isolated in 19% yield.
