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 take place that would not occur as an intermolecular reaction between two compounds.
In this particular reaction the tether angle bringing the reactive groups together is effectively reduced by placing isopropyl groups on the silicon atom via the Thorpe-Ingold effect. No reaction takes place when these bulky groups are replaced by smaller methyl groups.
Another example is a photochemical [2+2]cycloaddition with two alkene groups tethered through a silicon acetal group (racemic, the other enantiomer not depicted) which is subsequently cleaved by TBAF yielding the endo-diol.
Without the tether the exo isomer forms .
Intramolecular cyclization reaction--palladium(0)-catalyzed cyclization is more effective than tin hydride mediated reaction.(Report)
Apr 01, 2008; Abstract: Intramolecular CH arylation of pyrone, pyridone, uracil, imidazole, and benzimidazole derivatives are carried...
Intramolecular hydroamination of unactivated alkenes with secondary alkylamines catalyzed by iridium phosphino-phenolate complexes.(Report)
Aug 01, 2010; Introduction The prevalence of nitrogen-containing moieties in both naturally occurring and biologically active molecules has...