[LeoLeoBest]

I want to introduce a functional group (e.g. Carboxyl, amine) to the benzene ring of PETG (2-phenylethyl β-D-thiogalactoside), does anyone have some suggestions on the synthetic route? In addition, the functional groups should be tethered to the benzene ring with a rigid linker, the substitution reaction is preferred at an orthogonal position. Thanks!

[billnotgatez]

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[AWK]

Rather no chance of functionalization of the phenyl group in the glycoside. Think about synthesizing the appropriate aglycone and forming a glycosidic bond in the last steps of the synthesis.

[LeoLeoBest]

I was actually considering using Friedel-Crafts Acylation perhaps with succinic anhydride, it is possible?

[LeoLeoBest]

Rather no chance of functionalization of the phenyl group in the glycoside. Think about synthesizing the appropriate aglycone and forming a glycosidic bond in the last steps of the synthesis.

How about using Friedel-Crafts Acylation with Succinic anhydride?

[kriggy]

I was actually considering using Friedel-Crafts Acylation perhaps with succinic anhydride, it is possible?

Everything is possible but I would expect some sugar side reaction under the acidic conditions.

[AWK]

PETG is a rather expensive reagent and not very stable.
Succinoyl group, being a bulky group, usually avoids the ortho position.
I wish you success, although I don't believe in it.

[rolnor]

It seems very bad mix a glycoside with AlCl3 and succinoylchloride, it will be a complete mess. All the OH-groups will be acylated and the succinoylchloride can form cyclic esters or dimer-polymer-esters. You need to se how PETg is synthesized and go in early with a good substituent on the aromatic ring.

[Babcock_Hall]

Echoing Rolnor, I would worry that the hydroxyl groups will react with reagents used to modify the ring.  I think that AWK has the right approach:  Modify the aromatic ring first, then attach it to glucose.