methyl (2S)-2-amino-3-[(2-methylpropan-2-yl)oxy]propanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To 4.43 g of Z-Ser(But)-OH and 3.18 g of HCl.H-Ser(But)-OMe in 30 ml of dimethylformamide are added at 0° 1.89 ml of N-ethylmorpholine, 2.29 g of HOBt and 3.4 g of dicyclohexylcarbodiimide. After standing for 2 hours at 0° and for 15 hours at 20°, the resulting product is filtered off, the filtrate is concentrated by evaporation and taken up in ethyl acetate. After extraction of the solution with sodium bicarbonate, dilute hydrochloric acid and water, the solution is concentrated by evaporation to leave as oil Z-Ser(But)-Ser(But)-OMe; Rf (toluene/acetone 1:1)=0.70. the resulting product is filtered off the filtrate is concentrated by evaporation After extraction of the solution with sodium bicarbonate, dilute hydrochloric acid and water the solution is concentrated by evaporation

Conditions: temp:20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 16.25 g of Z-Thr(But)-OSu and 8.47 g of H-Ser(But)-OMe. HCl are added to 200 ml of ethyl acetate, 5.6 ml of triethylamine are added at 0°C and the solution is stirred for 15 hours at 20°C and washed with 1 N citric acid, 1 N sodium bicarbonate and water. After drying over sodium sulphate, the solution is evaporated, whereupon the product, which is pure according to thin layer chromatography, is obtained as an oil. are added at 0°C washed with 1 N citric acid, 1 N sodium bicarbonate and water After drying over sodium sulphate the solution is evaporated, whereupon the product, which is obtained as an oil