1 DFJ N-({4-[difluoro(phosphono)methyl]phenyl}acetyl)-L-phenylalanyl-4-[difluoro(phosphono)methyl]-L-phenylalaninamide 1.000 2 DFM N-acetyl-L-phenylalanyl-4-[difluoro(phosphono)methyl]-L-phenylalaninamide 0.717