CAS 40356-52-3 appears in our catalog under these names: Z-Pyr-onp, 95%, (S)-1-Benzyl 2-(4-nitrophenyl) 5-oxopyrrolidine-1,2-dicarboxylate, 95+%, Z-L-Pyr-ONp, Z-L-pyroglutamic acid 4-nitrophenyl ester. Offered by: Combi-blocks, AmBeed, Iris Biotech, Biosynth. Available pack sizes: 1g, 25g, 5g, 100g.