反应详情

(R)-tert-butyl 3-(tert-butyldimethylsilyloxy)-1-oxo-1-phenylpropan-2-ylcarbamate (23) (1.5 g, 4.0 mmol, 1.0 equiv.) was added to a 100 mL RBF followed by a 1:1 mixture of THF/H2O (20 mL). The mixture was stirred and glacial acetic acid (30 mL) was added to the reaction flask. The reaction stirred for 22 h at rt. The reaction was transferred to a 500 mL separatory funnel with sat. NaCl (75 mL) and sat. NaHCO3 (50 mL). The aqueous layer was extracted with EtOAc (3×75 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 1.3 g of crude material. The residue was purified by flash column chromatography (40% EtOAc/hexanes) to give 1.0 g (95%) of 24 as a colorless oil which crystallized to a white solid. Rf=0.27 (40% EtOAc/hexanes); mp=60-62° C.; [α]D23.5=+12.4 (c 1.01, MeOH); IR (KBr) 3420, 2976, 2931, 1683, 1503, 1366, 1165, 1061 cm-; 1H NMR (500 MHz, CDCl3) δ 8.00 (d, J=7.5 Hz, 2H, Ph-H), 7.62 (t, J=7.5 Hz, 1H, Ph-H), 7.51 (t, J=7.5 Hz, 2H, Ph-H), 5.88 (br s, 1H, carbamate-NH), 5.35 (br s, 1H, Boc-NH—CH), 4.02 (m, 1H, CH—CH2), 3.86 (m, 1H, CH—CH2), 2.91 (br s, 1H, CH2—OH), 1.47 (s, 9H, t-butyl-CH3); 13C (125 MHz, CDCl3) δ 197.4, 156.3, 134.6, 134.1, 129.0, 128.9, 80.5, 64.7, 58.1, 28.4; LRMS (ESI-MS m/z): Mass calcd for C14H19NNaO4 [M+Na]+, 288.29. Found 288.

1. stirringThe reaction stirred for 22 h at rt
2. extractionThe aqueous layer was extracted with EtOAc (3×75 mL)
3. dry with materialthe combined organic layers were dried over Na2SO4
4. concentrationThe solution was then concentrated on a rotary evaporator
5. customdried under vacuum
6. customto give 1.3 g of crude material
7. customThe residue was purified by flash column chromatography (40% EtOAc/hexanes)