The general procedure for synthesizing DL-tert-leucine from D-tert-leucine is as follows:
Example 3A: A 30% ammonium hydroxide solution (50 mL) was added to the autoclave, followed by D-tert-leucine (5 g). The autoclave was sealed and the mixture was heated to 85°C under stirring conditions and maintained at this temperature for 12 hours of reaction. Upon completion of the reaction, the reaction mixture was cooled and the solution was transferred to a rotary evaporator and concentrated under vacuum at 55 °C. The solid residue obtained after concentration was mixed with acetone (20 mL) with stirring, followed by filtration and drying to finally obtain DL-tert-leucine (4.6 g, 92% yield, of which the L-isomer accounted for 42% and the D-isomer for 58%).
