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(R)-tert-butyl 3-(tert-butyldimethylsilyloxy)-1 (methoxy(methyl)amino)-1-oxopropan-2-ylcarbamate (22) (2.2 g, 6.0 mmol, 1.0 equiv.) was added to a 250 mL RBF followed by THF (60 mL). The mixture was cooled to 0° C. via an ice bath and a 1.0 M solution of PhMgBr in THF (18.0 mL, 18.0 mmol, 3.0 equiv.) was added over 8 min. The reaction stirred for 1.0 h at 0° C. and the ice bath was removed. The reaction stirred for an additional 1.0 h at rt. and was again cooled to 0° C. via an ice bath. Next, the reaction was quenched by addition of 1.0 M HCl (55 mL). The solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL) and extracted with EtOAc (3×100 mL). The organic layers were washed with sat. NaCl (1×50 mL) and dried over Na2SO4. The solution was then concentrated on a rotary evaporator and dried under vacuum to give 2.5 g of crude material. The residue was purified by flash column chromatography (10% EtOAc/Hexanes) to give 2.0 g (89%) of 23 as a colorless oil. Rf=0.29 (10% EtOAc/Hexanes); [α]D23.5=−12.3 (c 1.26, MeOH); IR (film) 3433, 3360, 3062, 2952, 2929, 2883, 2856, 1715, 1688, 1498, 1253, 1167, 1114 cm−1; 1H NMR (500 MHz, CDCl3) δ 7.97 (d, J=7.0 Hz, 2H, Ph-H), 7.61 (t, J=7.0 Hz, 1H, Ph-H), 7.50 (t, J=7.0 Hz, 2H, Ph-H), 5.73 (d, J=7.5 Hz, 1H, carbamate-NH), 5.35 (m, 1H, Boc-NH—CH), 3.97 (dq, J=9.5, 2.5 Hz, 2H, CH—CH2), 1.50 (s, 9H, Boc-t-butyl-CH3), 0.79 (s, 9H, Si-t-butyl-CH3), −0.07 (s, 3H, Si—CH3), −0.12 (s, 3H, Si—CH3); 13C (125 MHz, CDCl3) δ 197.9, 155.5, 135.6, 133.5, 128.8, 128.7, 79.9, 64.5, 57.4, 28.5, 25.8, 18.2, −5.6, −5.7; LRMS (ESI-MS m/z): Mass calcd for C20H33NO4Si [M]+, 379.57. Found 380.

1. customthe ice bath was removed
2. stirringThe reaction stirred for an additional 1.0 h at rt
3. temperatureand was again cooled to 0° C. via an ice bath
4. customNext, the reaction was quenched by addition of 1.0 M HCl (55 mL)
5. customThe solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL)
6. extractionextracted with EtOAc (3×100 mL)
7. washThe organic layers were washed with sat. NaCl (1×50 mL)
8. dry with materialdried over Na2SO4
9. concentrationThe solution was then concentrated on a rotary evaporator
10. customdried under vacuum
11. customto give 2.5 g of crude material
12. customThe residue was purified by flash column chromatography (10% EtOAc/Hexanes)