Hydrochloric Acid → ethyl (2R)-2-amino-3-cyclohexylpropanoate

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The process is performed as in Example 2, starting with 10 g of β-cyclohexyl-(D)-alanine hydrochloride in 96 cm3 of absolute ethanol, by treating it with a stream of dry hydrogen chloride at a temperature in the region of 0° C. for 20 minutes. After heating to about 80° C. for 4 days, followed by cooling to 0° C., the mixture is again treated with a stream of hydrogen chloride for 20 minutes, followed by heating to a temperature in the region of 80° C. for 20 hours. The reaction medium is concentrated under reduced pressure (5 kPa) at a temperature in the region of 40° C., and the residue obtained is dissolved in 200 cm3 of water, made alkaline by addition of 19 g of solid potassium carbonate. After evaporation, the resulting solid is taken up in 200 cm3 of ethanol at a temperature in the region of 80° C. The insoluble material is filtered off and the filtrate is evaporated under reduced pressure (5 kPa) at a temperature in the region of 40° C. The residue obtained is taken up in 130 cm3 of ethanol at room temperature. The insoluble material is filtered off and the filtrate is again evaporated under the same conditions as above. 4.8 g of ethyl (2R)-2-amino-3-cyclohexylpropionate are obtained in the form of a whitish paste. (Rf=0.80 in a 90/10 by volume mixture of ethanol/aqueous ammonia, on a Merck 60F254R silica plate)

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