Dl-cysteine derivs and inactive cystine

摘要

derivs. and inactive cystine Crude alpha-amino-beta-ethoxypropionic acid (obtained e.g. by reaction of alpha-bromo-beta-ethoxypropionic acid with NH3) is reacted in the presence of acetic anhydride with a thio-acid or thiourea, then hydrolysed with acid or alkali and oxidized (e.g. with H2O2 or air) to give inactive cystine. Alternatively, the hydrolysis product (D, L-cysteine) may be reacted with dicyandiamide to give DL-2-guanidino-2-thiazoline-4-carboxylic acid or benzylated and/or acetylated to give benzylcysteine, acetylcysteine or benzylacetylcysteine.