反应详情

A solution of semicarbazone 233e (390 mg, 0.68 mmol) in methanol (10 ml) was cooled at 0° C. and then treated with a 38% aq. solution of formaldehyde (2 ml) and 1M HCl (2 ml). The reaction mixture was then stirred overnight at room temperature. The solution was concentrated to remove the methanol. The aq. solution was extracted with EtOAc (30 ml). The organic solution was successively washed with 10% NaHCO3 (30 ml) and sat. aq. NaCl (30 ml), dried (MgSO4) and concentrated. Purification by flash chromatography or silica gel (2-5% methanol in CH2Cl2) afforded 234e (179 mg, 51% as a white foam: [α]D20 −101° (c 0.064, MeOH; IR (KBr)3346, 2976, 2934, 1730, 1657, 1535, 1456, 1425, 1278, 1255, 1156, 708; 1H NMR (CDCl3) δ9.56 (1H, s), 7.88-7.38 (5H, m), 7.01 and 6.92 (2H, 2d) 5.27-5.08 (2H, m), 4.69-4.46 (1H, m), 3.50-3.27 (2H, m), 3.15-2.73 (2H, m), 2.46-1.83 (10H, m), 1.43 (9H, s).

1. concentrationThe solution was concentrated
2. customto remove the methanol
3. extractionThe aq. solution was extracted with EtOAc (30 ml)
4. washThe organic solution was successively washed with 10% NaHCO3 (30 ml) and sat. aq. NaCl (30 ml)
5. dry with materialdried (MgSO4)
6. concentrationconcentrated
7. customPurification by flash chromatography or silica gel (2-5% methanol in CH2Cl2)