Methanol → Boc-Cha-OMe

Participants

Reaction Conditions

Reaction Steps

After 25.0 ml (19.8 wt %) of methanol was added to 100 g of oily N-t-butyloxycarbonyl-3-cyclohexyl-L-alanine at room temperature (about 25° C.), the mixture was heated to 40° C. while stirring. When the temperature of liquid reached 40° C., methanol was evaporated under reduced pressure. Oily N-t-butyloxycarbonyl-3-cyclohexyl-L-alanine methyl ester was again obtained. Crystals of N-t-butyloxycarbonyl-3-cyclohexyl-L-alanine methyl ester prepared in Example 1 (1.0 g) were added to the oil as seed crystals. Cooling was gradually continued to 15° C. while stirring. The precipitated crystals were immediately separated by centrifuging, and were then washed with 5 ml of previously cooled methanol. After the obtained crystals were air-dried, the crystals were further dried at 30° C. overnight under reduced pressure to give 84.3 g of N-t-butyloxycarbonyl-3-cyclohexyl-L-alanine methyl ester as crystals. The powder X-ray chart for the crystals formed in this way resembled that shown in FIG. 1 for the crystals of Example 1.

Provenance & Evidence