Fluoride-induced proto- and carbo-desilylation of S,S-, O,O- and O,S-silylated acetals: an insight into the chemical and stereochemical reaction outcome

A general overview on the chemical and stereochemical behavior of a wide range of stereodefined 2-silyl-1,3-dithianes, -1,3-dioxanes, -1,3-dioxolanes and -1,3-oxathiolanes is reported, when subjected to fluoride ion-induced proto- and carbo-desilylation. Retention of configuration or epimerization appears to depend not only on the kind of the substituents on the aromatic ring, but also on the nature of heteroatoms in the silyl acetals, leading to envisage the occurence of a free carbanion or of an hypervalent-silylated species.