| Lignans and neolignans are a large group of
natural products characterised by the |
| coupling of two C6C3
units. For nomenclature purposes the C6C3 unit is treated
as |
| propylbenzene and numbered from 1 to 6 in
the ring, starting from the propyl group, |
| and with the propyl group numbered from 7
to 9, starting from the benzene ring. |
| With the second C6C3
unit the numbers are primed. When the two C6C3 units
are |
| linked by a bond between positions 8 and 8'
the compound is referred to and named |
| as a lignan. In the absence of the C-8 to
C-8' bond, and where the two C6C3 units |
| are linked by a a bond between positions 8
and 8' the compound is referred to and |
| named as a lignan. In the absence of the C-8
to C-8' bond, and where the two C6C3 |
| units are linked by a carbon-carbon bond it
is referred to and named as a neolignan. |
| The linkage with neolignans may include C-8
or C-8'. Where there are no direct |
| carbon-carbon bonds between the C6C3
units and they are linked by an ether |
| oxygen atom the compound is named as an oxyneolignan.
The nomenclature |
| provides for the naming of additional rings
and other modifications following |
| standard organic nomenclature procedures for
naming natural products. Provision is |
| included to name the higher homologues. The
sesquineolignans have three C6C3 |
| units and dineolignans have four C6C3
units. |
