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Since silicon is quite abundant in the earth's crust, its utilization in organic synthesis, material science, and medicinal science is highly desirable. We have developed new catalytic silylation reactions on the basis of activation of the silicon-containing σ-bond by transition metal catalysts.

Bis-Silylation

For instance, intramolecular bis-silylations have been developed on the basis of our finding on new palladium catalysts, i.e., palladium-isocyanide catalysts [Ref .1], for the activation of the Si-Si bond. The intramolecular reactions enabled the synthesis of enantioenriched allylsilanes [Ref. 2], allenylsilanes [Ref. 3] and polyols [Ref. 4] in stereoselective fashions.

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

Silaborations

We established that the Si-B bond shows remarkable selectivity and reactivity in the presence of transition metal catalysts [Ref. 5]. We could establish a variety of catalytic reactions involving (1) simple addition reactions (silaborations) [Ref. 6], (2) silaborative C–C coupling reactions [Ref. 7], and (3) silaborative cleavage of C-C bonds in small rings [Ref. 8]. In addition, recent success in synthesizing Si-functionalized silylboranes [Ref. 9, see also Ref. 10] allowed us to find that (dialkylamino)diorganosilylboranes serves as a synthetic equivalent of “silylene” [Ref. 11]. Typical catalytic reactions we have so far developed are shown below.

silaboration_s.jpg
 

References

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