Bridged compounds

Hexamine

Bridged compounds are compounds which contain interlocking rings.

Examples include:

Nomenclature

The nomenclature of bridged compounds was established by the von Baeyer system. Some important concepts for bridged compounds are:

Bridgehead: Any skeletal atom of the ring system which is bonded to three or more skeletal atoms (excluding hydrogen). In consequence, the bridgeheads are always tertiary or quaternary carbons. For insaturations, Bredt's rule states that a double bond cannot be placed at the bridgehead of a bridged ring system, unless the rings are large enough.
Bridge: Unbranched chain of atoms or an atom or a valence bond connecting two bridgeheads. They may consist in carbon or heteroatoms. (Excluding hydrogen)
Main ring: Ring identified as the pattern structure.
Main bridge: Bridge which connects the two bridgeheads in pattern structure.
Secondary bridge: Any bridge not included in the main ring or the main bridge.

Bridged Compounds at the US National Library of Medicine Medical Subject Headings (MeSH)
Rule A-31. Bridged hydrocarbons. Bicyclic Systems IUPAC Blue Book
Rule A-32. Bridged Hydrocarbons. Polycyclic Systems IUPAC Blue Book
Rule A-34. Hydrocarbon Bridges. Bridged Hydrocarbons IUPAC Blue Book
Rule B-14. Bridged Heterocyclic Systems. Extension of the von Baeyer System. IUPAC Blue Book