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Intramolecular reactions in which two reactive moieties are connected through removable tethers are attractive strategy in organic synthesis, because higher reactivity and selectivity than the corresponding intermolecular reaction are expected.

Intramolecular Bis-Silylation

Intramolecular silylations with the tethered silicon atom was particularly attractive. We actually found that intramolecular variants of bis-silylations exhibited high reactivities, higher stereoselectivities, and higher applicability to organic synthesis. Through stereoselective intramolecular bis-silylation of homoallylic alcohols, we made stereoselective total synthesis of (–)-Avenaciolide [Ref. 1]. We also established a synthetic access to highly enantioenriched allylsilanes by intramolecular bis-silylation of allylic alcohols through highly efficient chirality transfer [Ref. 2]. In a similar manner, enantioenriched allenylsilanes are synthesized from enantienriched propargyl alcohols [Ref. 3].

avenaciolide synthesis via bis-silylation80.jpg
 
allylsilane synthesis via bis-silylation80.jpg
 
allenylsilane synthesis via bis-silylation80.jpg
 

Intramolecular Cyanoboration

We have also developed intramolecular borylations [Ref. 4]. Intramolecular cyanoboration, for instance, proceeded with high regio- and stereoselectivity than the corresponding intermolecular cyanoboration. Highly substituted a,b-unsaturated nitriles were prepared from the cyanoboration products.

intramol. cyanoboration80.jpg
 

Related Researches

References

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Last-modified: 2009-01-21 (水) 18:12:32 (4700d)