3-Benzyl-hexahydro-pyrrolo[1,2-a]pyrazine-1,4-dione Diketopiperazine cyclo(D-Pro-D-Phe) InChI=1/C14H16N2O2/c17-13-12-7-4-8-16(12)14(18)11(15-13)9-10-5-2-1-3-6-10/h1-3,5-6,11-12H,4,7-9H2,(H,15,17)/t11-,12-/m0/s pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)-, (3S,8aS)- rel-(3R,8aR)-3-benzylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione