Oligosilanes rearrangement

Recently, Tamao and coworkers have found that palladium catalyzed the skeletal rearrangement of alkoxy(oligosilanes) (equation 56), presumably via formation of a silyloxy base-stabilized silylene complex (106) (equation 57)256. 

Similar generation of palladium-silylene complexes may be involved in reaction of oligosilanes with aryl isonitriles giving four-membered rearranged products 95, although the mechanism has not yet been clarified (Eq.49) [81,86]. 

A fair number of other synthetically useful ways to form SiASi bonds exists. An incomplete list comprises electrochemical methods, dehydrocoupUng of hydrosilanes, cycloaddition reactions, rearrangement reactions, silylene insertion, and radical recombination. Most of these will be shown or described in the following sections outlining the formation and reactivity of different types of oligosilanes. 

Scheme 12 Lewis acid catalyzed rearrangement processes of permethylated oligosilanes and...

A subsequent study in this field revealed that the rearrangement of certain branched acyclic oligosilanes can also lead to the formation of substituted cyclopentasilanes, which occurs with elimination of tetramethylsilane (7) [123]. 

Scheme 14 lodination of a stable persilapropellane to a hexaiodocyclopentasilane Equation 7. Lewis acid catalyzed rearrangement/cyclization of an oligosilane. 

Equation 8. Lewis acid catalyzed rearrangement of a ttimethylgermylated oligosilane with formal germanium migration. 

Wagner H, Baumgartner J, Marschner C, Poelt P (2011) Rearrangement/fragmentation reactions of oligosilanes with aluminum chloride. Organometallics 30 3939... 

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