Guys, this is a hard problem. Let me go ahead and read it, and then we'll try to work through it together. In aqueous base, D-glucose has the ability to epimerize into small amounts of D-mannopyranose and also rearrange into D-fructofuranose. Fischer glycosylation can then transform these saccharides into O-glycosides. So the two-part question says, a) predict the structure of the glycoside products after treatment with acid and methanol, and b) how could the treatment of those glycosides with periodic acid distinguish if epimerization or rearrangement is more favored? Cool. So that was a mouthful.

Guys, so this is what it's basically saying in the first little sentence. It's saying that D-glucose, through two separate processes, can either become one thing or another. Okay. Now I have videos on both of these processes, on epimerization and rearrangement. So if you're really curious about how to get these exact cyclic sugars, then please go ahead and watch those videos. But because this is beyond the scope of this question, I'm not going to draw out the exact way that we got to these sugars in this question. Okay? Because what we're really trying to focus on is what happens after these form. Just take my word for it that D-glucose can provide these two cyclic sugars, a furanose and a pyranose.

Now where the question really starts is it says, okay, predict the structure of the O-glycosides that would form after each of these is treated with methanol and acid. This part is actually pretty easy because you should have learned about O-glycosylation already or also Fischer glycosylation, and you should be familiar with which alcohols react when you react with alcohol and acid. Do you remember? Notice that all of the Os are missing their Hs, so we're going to have to predict together if it remains as an alcohol or if it gets a methyl group on it. So what do you think? Here I have 1, 2, 3, 4, 5 potential