13-Oxa-2,6,11-triazapentadecanoic acid, 14,14-dimethyl-12-oxo-, phenylmethyl ester 68076-38-0 N(1)-Benzyloxycarbonyl-N(8)-butoxycarbonylspermidine N(1)-Z-N(8)-Boc-spermidine NZBS