Molecule 1.
Base: Furan (Rule 2. component with higher priority heteroatom)
Annex: Thiophene (thiene)
Annexed numbering: starts at the sulfur and goes towards the C. bridge.
Literature base: it begins in the oxygen and goes towards the C. bridge.
Peripheral numbering: start at oxygen to give the lowest locants to the heteroatoms. (rule 1)
Name: Thieno [3,4-b] furan
Molecule 2.
Base: Pirano (Rule 3. component with the largest of the rings)
Attached: Furan (furo)
Annexed numbering: starts at the sulfur and goes towards the C. bridge.
Literature base: it begins in the oxygen and goes towards the C. bridge.
Peripheral numbering: start at oxygen to give the lowest locants to the heteroatoms. (rule 1)
Name: 2H- Furo [3,2-b] pyran
Molecule 3.
Base: Oxazine (Rule 4. component with more heteroatoms)
Annexed: Pyridine (Pyrido)
Numbering annexed: it begins in the nitrogen and goes towards the C. bridge.
Literature base: it begins in the oxygen and goes towards the C. bridge.
Peripheral numbering: it begins in the nitrogen next to the bridgehead and continues further away from it.
Name: 5H- Pyrido [2,3-d][1,2] oxazine
Molecule 4.
Base: Oxazole (Rule 5. component with the greatest variety of heteroatoms)
Added: Pyrazole (Pyrazolo)
Name: 1H- Pyrazolo [4,3-d][1,3] oxazole
Molecule 5.
Base: Dithiazine (Rule 6. component with the highest number of heteroatoms of greatest preference)
Annexed: Thiadiazine (Thiadiazine)
Name: 4H-[1,2,3]Thiadiazine[4,5-e][1,2,4]dithiazine
Molecule 6.
Base: Pyridazine (1,2-diazine) (Rule 7. component that, before condensation, has the least locants for its heteroatoms)
Annexed: Pyrazine (1,4-diazine) (Pyrazino)
Name: Pyrazino[2,3-d]pyridazine
Molecule 7.
Base: 1,2,3-Oxathiazole (Rule 8. Rule 7 considering the priority of heteroatoms)
Annex: 1,2,3-Oxazathiazole (1,2,3-Oxazathiazole)
Name: 3H,5H-[1,2,3]Oxazathiazolo[4,5-d][1,2,3]oxathiazole
Molecule 8.
Base: 1,3-thiazole (Rule 5. component with the greatest variety of heteroatoms)
Addendum: Imidazole (Imidazolo)
Name: 5-Methylimidazolo[2,1-b][1,3]thiazole
Note: Note that the outer numbering includes the bridging atom when it is a heteroatom .