Spectrum of armed and disarmed glycosides

From the analogy between the cationic structure of the protonated piperidine and the oxacarbenium ion-like transition state in glycoside hydrolysis, one can explain why galactosides were 5-fold more reactive than glucosides and why the removal of the OH group leads to a further increase in reactivity towards hydrolysis. 

The destabilization of oxocarbenium ions ( disarming of saccharide ) can also arise from the loss of anomeric stabilization imposed by structural effects in rigid polycyclic structures. Formation of oxycarbenium 

The high reactivity of orthoesters can be used for initiation of cationic reactions under relatively mild conditions. Acid hydrolysis of myo-inositol 1,3,5-orthoformates proceeded within 15min in 10 1 mixture of TFA water at room temperature. The resulting bridged ions can be trapped in a variety of inter- and intramolecular 

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