Intramolecular

Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule, a property or phenomenon limited to the extent of a single molecule.

In intramolecular organic reactions, two reaction sites are contained within a single molecule. This creates a very high effective concentration (resulting in high reaction rates), and, therefore, many intramolecular reactions that would not occur as an intermolecular reaction between two compounds take place.

Examples of intramolecular reactions are the Smiles rearrangement, the Dieckmann condensation and the Madelung synthesis.

In a niche concept called molecular tethers, otherwise-intermolecular reactions can be made temporarily intramolecular by anchoring both reactions by a tether with all the advantages associated to it. Popular choices of tether contain a carbonate ester, boronic ester, silyl ether, or a silyl acetal link (silicon tethers) which are fairly inert in many organic reactions yet can be cleaved by specific reagents. The main hurdle for this strategy to work is selecting the proper length for the tether and making sure reactive groups have an optimal orientation with respect to each other. An examples is a Pauson-Khand reaction of an alkene and an alkyne tethered together via a silyl ether

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