Nomenclature of Heterocycles

Flashcards for Heterocyclic Nomenclature

Heterocyclic Rings

Heterocyclic rings may consist of one or more heteroatoms such as oxygen, nitrogen, and sulfur.

Numbering Order of Heteroatoms

The order of numbering when heteroatoms exist together in a ring is O > S > N.

Oxa

Oxygen

Aza

Nitrogen

Thia

Sulfur

….ole

Five-membered rings

….ine

Six-membered rings

….epine

Seven-membered rings

H or Hydro

Indicates a saturated corner in a heterocyclic system.

Benzo

Indicates an heterocyclic ring fused with benzene.

Dibenz

If an heterocyclic ring is fused with two benzene rings.

1,3-oxazole

An example of heterocyclic nomenclature

1,3,4-thiadiazole

An example of heterocyclic nomenclature

1,3-diazine

An example of heterocyclic nomenclature, also known as Pyrimidine

1H-azepine

An example of heterocyclic nomenclature

6H-1,3-thiazine

An example of heterocyclic nomenclature

2H-1,3-benzoxazine

An example of heterocyclic nomenclature

Furane Tetrahydrofurane

An example of heterocyclic nomenclature

2H-1,2,4-benzothiadiazine

An example of heterocyclic nomenclature

benzo(b)pyridine

An example of heterocyclic nomenclature

3H-1,4-benzodiazepine

An example of heterocyclic nomenclature

10,11-dihydrodibenz(b,f)azepine

An example of heterocyclic nomenclature

Fused Heterocyclics

Write the two heterocyclic rings separately, join them, add heteroatoms, and number them.

1H-pyrazolo [4,3-d] oxazole

An example of heterocyclic nomenclature

Pyrazino [2,3-d]pyridazin

An example of heterocyclic nomenclature

2H-furo [3,2-b]pyran

An example of heterocyclic nomenclature

Bicyclic Rings

Two or more atoms belong to two or more rings; numbering starts from the bridge atom.

Bicyclo[4.1.0]heptane

An example of heterocyclic nomenclature

Bicyclo[1.1.0]butane

An example of heterocyclic nomenclature

Spiro Hydrocarbones

Ring systems where only one atom belongs to two rings; number the smaller ring first, starting from the top corner.

spiro[3.5]nonane

An example of heterocyclic nomenclature

spiro[4.5]decane

An example of heterocyclic nomenclature