反应详情

A solution of the amide from step 2 above (4.2 g) in dichloromethane (60 ml) and trifluoroacetic acid (20 ml) was refluxed for 4 hours. The reaction mixture was concentrated to dryness and the residue was submitted to chromatography on silica gel using dichloromethane-ethyl acetate (6:4) as eluent. The first fraction was concentrated to dryness and the residue was crystallized from methanol giving diastereomer I, m.p. 135-140° C. The third fraction contained diastereomer II, which was recovered as an amorphous solid.

1. concentrationThe reaction mixture was concentrated to dryness
2. concentrationThe first fraction was concentrated to dryness
3. customthe residue was crystallized from methanol giving diastereomer I, m.p. 135-140° C
4. customwas recovered as an amorphous solid