Skeletal rearrangement of a bicylic 1,3-diphenyltrisilane during acid-induced dephenylation reactions

Protic and Lewis acid-induced dephenylation reactions of bis(tetramethylene)-tethered bicyclic 1,3-diphenyltrisilane 1 have been found to be accompanied by a facile skeletal rearrangement that forms the ring-contracted silyl-substituted bicyclic disilanes. For the reaction with a protic acid (HX), such as HCl/AlCl3 and trifluoromethanesulfonic acid (TfOH), the protonation of the ipso-carbon of the phenyl group would be followed by the nucleophilic attack of X− on the central silicon atom that induces the skeletal rearrangement. In the case of the reaction with boron trichloride, the same rearranged product was obtained as well, although the reaction mechanism is not clear.