Thursday, February 19, 2009

How to make beta anomer of sugar?

anomeric effect is effective when you have free -OH ( or ether protected) around the sugar ring.

So when you make a glycoside at the anomeric position, you will get a mixture of alpha and beta anomers.
Alghough alpha anomer is thermodynamically more stable, beta anomer formation is quicker.

how do you make beta anomer selectively?
one way is to protect the -OH on the sugar ring with ester (ex. acetate) which have small anomeric effect when you do reaction at anomeric position.

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