Dioxanylium salts

Pentanetriol tripivalate reacts - with antimony pentachloride to give the dioxanylium salt 46. The cation of 46 can rearrange into the ion 47, which remains structurally and energetically... 

In the following discussion, the dioxolanylium (2) and dioxanylium ring-systems will be referred to simply as acyloxonium derivatives, as the carboxonium ion of the ring is formally derived from a carboxylic acid. Thus, system 2 is an acetoxonium salt when R = Me, and a benzoxonium salt when R = Ph. 

The salt 52 is relatively stable thermally, and can be studied by variable-temperature, n.m.r. spectroscopy. At room temperature in nitromethane-rfs, the two expected fert-butyl signals (Av 20.2 Hz), in the intensity ratio of 1 2, are observed, and these signals coalesce at 110°. The methylene groups of the dioxanylium ring, and the... 

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