... Heterocyclic Chem., 21, 725 (1984). ... Chemical shifts (5 values) are in parts per million from tetramethylsilane. Coupling constants (J) are in Hz. [b] See reference [6]. Page 2. 726 S. Shiotani, H. Morita, M. Inoue, T. Ishida, Y. Iitaka and A. Itai Vol. ...