Nomenclature Of Medicinal Comp. Of

NOMENCLATURE OF HETEROCYCLIC COMPOUNDS By : Vishal Sachan

1.1 NOMENCLATURE

• In heterocyclic chemistry there is a special name for each individual ring system and a trivial name for each compound. Trivial names convey little or no structural information but they are still widely used. The systematic name, in contrast, is designed so that one may deduce from it the structure of the compound. They tend to be long. However, a systematic nomenclature is still indispensable. • In recent years the International Union of Pure and Applied Chemistry (IUPAC) has made efforts to systematize the nomenclature of heterocycliccompounds. •According to this system single three-to-ten-membered rings are named by combining the appropriate prefix or prefixes (listed in Table 1.1) with a stem from Table 1.2.

Hetroatom

Table 1.1 Prefix for Hetero Atoms valence

O N

2 3

Prefix Oxa Aza

S

2

Thia

Se

2

Selena

P

3

Phospha

As

3

Arsa

Si

4

Sila

Table 1.2 Common Name Endings for Heterocyclic Compounds

Ring Size

Suffix for unsaturated compounds

With ‘N’

Without ‘N’

Suffixes for fully saturated compounds With ‘N’

With-out ‘N’

3

-irene

-iren

-iredine

-irane

4

-ete

-et(ete)

-etidine

-etane

5

-ole

-ole(ol)

-olidine

-olane

6

-ine

-in

perhydro ine

-ane

7

-epine

-epin

Perhydro epine

-epane

8

-ocine

-ocin

9

-onine

-onin

-perhydro ocine

-ocane --onan

-perhydro onine 10

-ecine

- Ecin

-ecan -perhydro ecin

Accordingly some examples of compounds named on the basis of above two tables are cited below:

Examples:

7 6

8

N

10

S

NH

N 2H-1,2,4-Benzothiadiazine

1

NH 2

5

9

1-Azabicyclo [4.2.0]octane

S

3 4

2H-1,2-benzothiazine