[kanonsviel]

Is it a named reaction? and does it involve a carbene?
And above all, what's the mechanism

[MissPhosgene]

Hint: a benzyl (Bn) acts as a nucleophilic species.

[kanonsviel]

So, you are suggesting that this is a SN2 reaction?
But what's the role is SnCl4 and CH2Cl2 playing
Is these two reagent added aimed to produced a carbene as I said?

[discodermolide]

So, you are suggesting that this is a SN2 reaction?
But what's the role is SnCl4 and CH2Cl2 playing
Is these two reagent added aimed to produced a carbene as I said?

No it's not SN2, the SnCl4 is acting as a Lewis acid, CH2Cl2 is a solvent. No carbene is involved

[NTUstudent]

I guess that SnCl4 activates carbon by bonding with -OR group!
but i am not sure.

[AWK]

This is Friedel-Crafts aryl C-glycosylation

[kanonsviel]

Based on your hint, I searched this reaction name, and the most useful information I got is this one showing below, but I couldn't get a detailed mechanism
It says "the substrates for Friedel–Crafts glycosylation are an activated glycoside donor (99,Fig. 13C) and an aryl acceptor (100)"
So based on this and discodermolide's suggestion, my assumption is like this:
1. one of the long pair of the OR group on C1 attacks the Sn atom, giving itself a positive charge, and thus makes itself a better leaving group
2. the benzene ring attacks C1, repelling the activated OR group
3. a base attacks the ortho hydrogen on the benzene ring, resuming its aromaticity

But if this is true, what's the base used in the third step?
Is it an OR anion or a Cl anion?

[discodermolide]

Based on your hint, I searched this reaction name, and the most useful information I got is this one showing below, but I couldn't get a detailed mechanism
It says "the substrates for Friedel–Crafts glycosylation are an activated glycoside donor (99,Fig. 13C) and an aryl acceptor (100)"
So based on this and discodermolide's suggestion, my assumption is like this:
1. one of the long pair of the OR group on C1 attacks the Sn atom, giving itself a positive charge, and thus makes itself a better leaving group
2. the benzene ring attacks C1, repelling the activated OR group
3. a base attacks the ortho hydrogen on the benzene ring, resuming its aromaticity

But if this is true, what's the base used in the third step?
Is it an OR anion or a Cl anion?

The OR group at the anomeric position attacks the Lewis acid and leaves to generate a carbonium ion which is stabilised by the ring oxygen atom. The electon rich aromatic ring (pi system attacks the anomeric carbon, giving the ring oxygen back it's full charge and creating an aromatic carbonium system which is stabilised by resonance. This picks up a proton to give the final product.

[kanonsviel]

I got it, so it undergoes a SN1-like mechanism in the first step.
Thanks very much.