CAS 52773-66-7 appears in our catalog under these names: Z-O-Benzyl-l-tyrosine hydroxysuccinimide ester, 95%, (S)-2,5-Dioxopyrrolidin-1-yl 2-(((benzyloxy)carbonyl)amino)-3-(4-(benzyloxy)phenyl)propanoate, 97%. Offered by: Combi-blocks, AmBeed. Available pack sizes: 1g, 25g, 5g.