Oxycarbenium salt

Initiators such as triethyloxonium salts, oxycarbenium salts (e.g., C6H5CO + A ), or dioxolenium salts initiate the polymerization by direct... 

Acylating agents (e.g., oxycarbenium salts) give both types of ring-openings. Active species of a-type re-form species a, and active species of type b (acylating species) form both a and b species after several further propagation steps, all b species are converted into a species [184],... 

A simplistic view of the mechanism is depicted in Scheme 3.5. The sulfoxide (I) is activated by triflic anhydride to generate a sulfonium salt (III). It was observed early on that the outcome of the glycosylation was not influenced by the configuration at the two variable stereogenic centers in the sulfoxide donor (i.e., anomeric carbon and sulfur).1 This was taken as evidence for the intermediacy of the oxycarbenium ion (V), which arises from rapid elimination of an alkylsulfenyl triflate(IV) from III. Reaction of V with a nucleophile then gives rise to a mixture of a- and P-glycosides (II). 

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