37553-66-5 Cyclo(L-pro-L-(N-Me)phe) Cyclo(L-prolyl-L-N-methylphenylalanyl) Cyclo(pro-(N-Me)phe) Cyclo(prolyl-N-methylphenylalanyl) Pyrrolo(1,2-a)pyrazine-1,4-dione, hexahydro-2-methyl-3-(phenylmethyl)-, (3S-trans)-