N-Carbobenzyloxy-L-aspartic acid Z-ASP(OTBU)-OH DCHA N-Cbz-L-Aspartic acid 4-tert-butyl ester Z-ASP(ONP)-OBZL Z-ASP(OSU)-OBZL Z-ASP(OBZL)-OSU Z-L-ASPARTIC ACID 4-BENZYL 1-(4-NITROPHENYL) ESTER Boc-L-aspartic acid 4-benzyl ester L-Aspartic acid dibenzyl ester 4-toluenesulfonate Boc-L-aspartic acid 1-benzyl ester