反应详情

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 0.20 g, 0.86 mmoles) was added to a room temperature solution of ((S)-1-Benzyl-2-oxo-ethyl)-carbamic acid benzyl ester (0.24 g, 0.86 mmoles) and 1,2-phenylenediamine (0.093 g, 0.86 mmoles) in CH3CN (10 mL). The reaction mixture was stirred at room temperature for 16 h, and then concentrated in vacuo. The residue was re-dissolved in EtOAc (150 mL), and washed with saturated aqueous NaHCO3 (3×125 mL). The organic layer was dried (MgSO4) and concentrated in vacuo to give a brown oily solid. Purification of the residue by flash chromatography on silica gel eluting with 10-40% EtOAc/heptane afforded 0.091 g (28% yield) of {(S)-1-Benzyl-2-[(E)-2-methylamino-phenylimino]-ethyl}-carbamic acid benzyl ester as a colorless oil: ES+ LC/MS m/e 372 (M+H), RT=3.03 min; 1H NMR (CDCl3) D9.90 (bd s, 1), 7.68 (bd s, 1), 7.21-7.33 (m, 11), 7.16 (d, 2, J=6.7 Hz), 5.64 (d, 1, J=7.2 Hz), 5.15 (dd, 1, J=15.2, 7.5 Hz), 5.07 (s, 2), 3.45 (d, 2, J=7.5 Hz).

1. concentrationconcentrated in vacuo
2. dissolutionThe residue was re-dissolved in EtOAc (150 mL)
3. washwashed with saturated aqueous NaHCO3 (3×125 mL)
4. dry with materialThe organic layer was dried (MgSO4)
5. concentrationconcentrated in vacuo
6. customto give a brown oily solid
7. customPurification of the residue by flash chromatography on silica gel eluting with 10-40% EtOAc/heptane