16908-49-9 2,2',2'',2'''-(Pyrimido(5,4-d)pyrimidine-2,4,6,8-tetrayltetrakis(methylimino))tetrakisethanol 2,4,6,8-Tetra(N-methyl-N-ethanolamino)pyrimido(5,4-d)pyrimidine AW-627 Awd 627 NSC 516474