反应详情

Trifluoroacetic acid (30 ml.) is added at 0° to a stirred solution of 4-t-butoxycarbonyl-3-[2-(methylthio)ethyl]piperazinone (XVII, Example 43, 2.6 g., 0.0095 mole) in diethyl sulfide (20 ml.). After 1 hour the solvents are removed and the residual oil is partitioned between chloroform (300 ml.) and 5N sodium hydrochloride solution (10 ml.). The chloroform is washed with water (2×10 ml.) and the chloroform is removed under reduced pressure. The residual oil is chromatographed on silica gel eluted with methanol:chloroform (1:9), the appropriate fractions are pooled and concentrated to give a solid which upon recrystallization from ethyl acetate:SSB gives the title compound, m.p. 68°-70°.

1. customAfter 1 hour the solvents are removed
2. customthe residual oil is partitioned between chloroform (300 ml.) and 5N sodium hydrochloride solution (10 ml.)
3. washThe chloroform is washed with water (2×10 ml.)
4. customthe chloroform is removed under reduced pressure
5. customThe residual oil is chromatographed on silica gel
6. washeluted with methanol:chloroform (1:9)
7. concentrationconcentrated
8. customto give a solid which
9. customupon recrystallization from ethyl acetate