[etheth]

Hello everyone,

I'm trying to convert an acetyl group on sugar to an azide by using TMSA and Sn(IV)Cl2 catalyst in CH2Cl2.
Can anyone tell me the mechanism of this reaction and how the catalyst works?
Many thanks for the *delete me*

[stewie griffin]

I'm not 100% sure on the exact mechanism, but I believe the basic idea is that tin is your lewis acid. It coordinates to the acetyl group's carbonyl oxygen, thus making it a better leaving group. The oxygen in the sugar ring then uses its lone pairs to kick out the acetyl group, thus making an oxocarbenium ion (which is just a better resonance description of a carbocation adjacent to an oxygen, BTW). The Me3SiN3 is just a source of azide, and the azide just does nucleophilic attack on the oxocarbenium ion.

[etheth]

thank you very much!
but is there a stable intermediate or some side conjugations formed?
I am unable to see my product mass in the MS.
thanks!

[stewie griffin]

Well is all of your starting material consumed? Also, what's your solvent, temp, reaction time?
I assume you're monitoring this reaction by TLC and MS?? You could also monitor by IR... you'd see your starting material's C=O stretch (around 1750 cm-1) disappear and the azide appear (though I can't remember where these signals come).
I suppose if your reaction isn't dry, then adventitious water could be the nucleophile istead of azide