| 1 | 255-01-6 | Pyrimido[4,5-e]-1,2,4-triazine (9CI) | C5H3N5 | 133.11 | | |
| 2 | 255-12-9 | 5H-Pyrimido[4,5-b][1,4]oxazine (8CI,9CI) | C6H5N3O | 135.12 | | |
| 3 | 255-13-0 | 7H-Pyrimido[4,5-b][1,4]oxazine (8CI,9CI) | C6H5N3O | 135.12 | | |
| 4 | 255-17-4 | 2H-1,4-Benzothiazine | C8H7NS | 149.21 | | |
| 5 | 255-30-1 | Pyrano[3,2-b]pyran(8CI,9CI) | C8H6O2 | 134.13204 | | |
| 6 | 255-368-7 | ETHYL CITRAL | C11H18O | 166.26 | | |
| 7 | 255-37-8 | 1,4-Benzodioxin | C8H6O2 | 134.13 | | |
| 8 | 255-50-5 | 1,4-Benzodithiin | C8H6S2 | 166.26 | | |
| 9 | 255-53-8 | Pyrazino[2,3-b]pyrazine | C6H6N4 | 134.13864 | | |
| 10 | 255-54-9 | [1,4]Dioxino[2,3-b]-1,4-dioxin(9CI) | C6H4O4 | 140.09356 | | |
| 11 | 255-55-0 | 1,4-DITHIINO[2,3-B]-1,4-DITHIIN, 97 | C6H4S4 | 204.36 | | |
| 12 | 255-80-1 | 4H-Pyrido[1,2-a]pyrimidine | C8H8N2 | 132.16 | | |
| 13 | 255-82-3 | Pyrido[1,2-a]pyrimidin-5-ium (8CI,9CI) | C8H7N2 | 131.155 | | |
| 14 | 255-85-6 | 4H,6H-Pyrido1,2-c1,3,5oxadiazine | C7H8N2O | 136.15 | | |