Reaction Steps
tertbutyl 3-(tert-butyldimethylsilyloxy)-1-oxo-1-phenylpropan-2-lmethylcarbamate (36) (640 mg, 1.6 mmol, 1.0 equiv.) was added to a 100 mL RBF followed by a 1:1 mixture of THF/H2O (8 mL). The mixture was stirred and glacial acetic acid (12 mL) was added to the reaction flask. The reaction stirred for 20 h at rt. The reaction was transferred to a 250 mL separatory funnel with sat. NaCl (50 mL) and sat. NaHCO3 (50 mL). The aqueous layer was extracted with EtOAc (3×70 mL) and the combined organic layers were dried over Na2SO4. The solution was then concentrated on a rotary evaporator and dried under vacuum to give 550 mg of crude material. The residue was purified by flash column chromatography (50% EtOAc/hexanes) to give 440 mg (97%) of 37 as a colorless oil. Rf=0.33 (50% EtOAc/hexanes); IR (film) 3451, 2975, 1681, 1149 cm−1; 1H NMR (500 MHz, CDCl3) δ Major rotamer: 7.96 (d, J=7.5 Hz, 1H, Ph-H), 7.90 (d, J=7.5 Hz, 1H, Ph-H), 7.58 (t, J=6.5 Hz, 1H, Ph-H), 7.46 (m, 2H, Ph-H), 5.45 (t, J=6.0 Hz, 1H, Boc-N—CH), 4.24 (m, 1H, CH—CH2), 4.14 (m, 1H, CH—CH2), 2.72 (s, 3H, Boc-N—CH3), 2.50 (m, 1H, CH2—OH), 1.43 (s, 9H, Boc-t-butyl-CH3). Minor rotamer: 4.89 (t, J=6.0 Hz, 1H, Boc-N—CH), 3.94 (m, 1H, CH—CH2), 3.81 (m, 1H, CH—CH2), 2.90 (s, 3H, Boc-N—CH3), 1.38 (s, 9H, Boc-t-butyl-CH3); 13C NMR (125 MHz, CDCl3) δ 199.9, 199.2, 156.1, 154.6, 135.7, 133.8, 128.9, 128.8, 128.5, 128.3, 81.7, 80.9, 63.5, 61.0, 60.8, 60.7, 33.3, 32.1, 28.4, 28.3; LRMS (ESI-MS m/z): Mass calcd for C15H21NO4Na [M+Na+], 302.32. Found 302.
