Abstract
Symmetric oxalates containing N-hydroxyimide or N-hydroxybenzotriazole group easily prepared from oxalyl chloride and N-hydroxyimide or N-hydroxybenzotriazole, are employed for the synthesizing of activated ester from corresponding N-protected amino acid. The active esters containing N-hydroxyimide or N-hydroxybenzotriazole derivatives react smoothly with nucleophiles such as amino acid to afford the corresponding dipeptides in high yields. In particular, N, N'-disuccinimidyl oxalate (DSO) is the most useful and easily handle reagent even in the synthesis of dipeptide of free carboxylic acid. In order to evaluate the local irritability of DSO, the eye and skin irritation tests were investigated with rabbit using DCC as a control substance. As shown in Table 1, 2 and Fig. 1 the local irritability of DSO was clearly weaker than that of DCC.
