# Why can't methyl glycosides mutarotate?

I found this link trying to explain it: Why pyranosides do not mutarotate? however, I don't understand a step of the reasoning.

Why is it that acetalisation needs a stronger acid than for hemi-acetalisation? I was wondering why can't the mechanism be similar to the the one for the mutarotation of glucose as shown below:

Couldn't the $$\ce{O}$$ break the bond, and then instead of forming the aldehyde, rotate the $$\ce{O-CH3}$$ group and then reform the bond?

• the second step, where the proton is removed by a base, woudn't work for a methyl group. Ether Cleavage needs a strong haloacid such as HI. – Aniruddha Deb Sep 2 '20 at 2:43
• @AniruddhaDeb ok, but can't I skip that step and just rotate then whole thing and then reform that bond? – John Hon Sep 2 '20 at 2:47
• You can’t skip a step. You either move along the pathway or you hit a dead end/wall. – Jan Sep 2 '20 at 15:12