Sodium Hydroxide → HCID 10222027, compound

Participants

Reaction Steps

1.65 g (3.99 mmol) of N-tert-butoxycarbonyl-3-(2-amino-4-bromophenylthio)-L-alanine methyl ester (98%) was dissolved in 65 ml TBME and emulsified in 240 ml buffer solution (0.1M sodium chloride; 20 mM sodium phosphate pH 7.5) under vigorous stirring. 0.75 ml Alcalase 2.4 L [a subtilisin Carlsberg from Novo Nordisk] was added and the pH maintained at 7.5 under vigorous stirring by the controlled addition (pH-static) of 1.0N sodium hydroxide solution. After 33 h, 4.23 ml of 1.0N sodium hydroxide solution was consumed and the conversion degree was >99% (HPLC analysis). The reaction mixture was acidified to pH 2 with 32% hydrochloric acid, filtered over Decalite. After phase separation the aqueous phase was extracted with 3×275 ml ethyl acetate. The combined organic phases were dried on anhydrous sodium sulfate and evaporated. The residue was dissolved in dichloromethane, evaporated and dried at HV to give 1.56 g N-tert-butoxycarbonyl-3-(2-amino-4-bromophenylthio)-L-alanine as a pale yellow solid (yield: 99.8%).

Provenance & Evidence