反应详情

Hydrogen chloride gas was bubbled in a slurry of 6-hydroxy-L-norleucine [prepared as described by Bodanszky et al., J. Med. Chem., 21, p. 1030-1035 (1978), 1.00 g., 6.9 mmol.] in dry methanol (35 ml.) until the mixture became homogeneous and began to reflux. The solution was then let cool and was stirred at room temperature for 2.5 hours. The methanol was removed by rotary evaporation and the residue was azeotroped twice with toluene to give crude 6-hydroxy-L-norleucine, methyl ester hydrochloride as a gum. Meanwhile, the dicyclohexylamine salt product from part (a) (3.506 g., 6.8 mmol.) was partitioned between 5% potassium bisulfate and ethyl acetate. The ethyl acetate extract was washed with additional 5% potassium bisulfate and brine, then dried (sodium sulfate), filtered and stripped to give N-phthalimido-L-tryptophan as the free acid.

1. temperatureto reflux
2. temperatureThe solution was then let cool
3. customThe methanol was removed by rotary evaporation
4. customthe residue was azeotroped twice with toluene