Mechanism of Protodephenylation of 1,3-Silaheterocyclohexanes. Effect of Heteroatom

The mechanism of electrophilic cleavage of the Si–Ph bond in 1,3-silaheterocyclohexanes is investigated. 3-Aryl-3-silatetrahydropyrans are shown to be less prone to the cleavage of the Si–Ph bond under the action of trifluromethanesulfonic acid than the corresponding 3-silathianes or silacyclohexanes. The effect of heteroatom (N, O, S) in the ring on the functionalization at the silicon atom in 1,3-silaheterocyclohexanes was studied experimentally by the method of NMR spectroscopy and theoretically by DFT calculations and the mechanism was suggested of dephenylation as a function of the nature of heteroatom.