MEM protection of carbohydrates

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In summary, the discussion revolves around the use of MEM and MOM groups for protecting carbohydrates. While these groups are commonly used for protecting alcohols, there seem to be limited examples of their use in carbohydrates. There is a concern about reactivity issues with these groups, as the sugars are hemiacetals and the ethers are acetals. Additionally, the limited solubility of sugars in polar aprotic solvents limits the types of reactions that can be performed on the OH groups. However, it is possible to make acetates and use them in different solvents for specific reactions.
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gravenewworld
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Would this work? I can't seem to find any examples in Scifinder of carbohydrates where all the -OH groups are protected with either MEM or MOM. Is there a reason why? Will this not work? I know using MEM and MOM are pretty standard for protecting alcohols, why in the case of carbohydrates does there seem to be little or no examples? There are examples in the literature of where people have added methyl groups n-butyl groups to make the ethers on all of the -OHs, would a MEM or MOM group work as well?
 
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Remember that the sugar is a hemiacetal and the MEM and MOM ethers are acetals so there will be reactivity issues if the cleavage reactions are needed later. Most of the reactions on sugar OH's are based on reactions that can be run in water since the sugars are largely insoluble in other polar aprotic solvents- it limits the electrophilic functions that can be used to react with the OH to ones that are able to be catalyzed and run in H2O. The common one is to make the acetates, and then use these (because they are differently soluble from the starting sugars) in ways that allow removal of a few groups and replace the protecting groups in aprotic solvents.

The sugar's hemiacetal is always targeted first for changing the solubility to make it a relatively stable acetal. It will usually allow for switching to MeCN or DMSO as a solvent, and a targeting of the OH's according to steric availability, and primary OH reactivity.
 
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1. What is MEM protection of carbohydrates?

MEM protection of carbohydrates is a chemical process used to modify the structure of carbohydrates. It involves adding a protecting group, called a MEM group, to the hydroxyl groups of the carbohydrate molecule. This modification is used to prevent unwanted reactions and to control the reactivity of the carbohydrate.

2. Why is MEM protection of carbohydrates important?

MEM protection of carbohydrates is important because it allows for selective reactions to occur at specific sites on the carbohydrate molecule. By temporarily masking certain functional groups, it allows for precise control over the reactions taking place. This is especially useful in organic synthesis and in the production of pharmaceuticals, where precise control over the chemical reactions is crucial.

3. How is MEM protection of carbohydrates carried out?

MEM protection of carbohydrates is carried out by reacting the carbohydrate with a reagent that contains a MEM group. This reaction is usually done in the presence of a base, such as sodium hydroxide, and in a solvent, such as dimethylformamide. The reaction conditions can be adjusted to control the degree of protection and the selectivity of the reaction.

4. What are the advantages of using MEM protection of carbohydrates?

There are several advantages to using MEM protection of carbohydrates. First, it allows for selective reactions to occur, which can be difficult to achieve with unprotected carbohydrates. Second, the MEM group is relatively stable and can withstand harsh reaction conditions, making it a versatile protecting group. Lastly, the MEM group can be easily removed after the desired reactions have taken place, leaving the original carbohydrate molecule intact.

5. Are there any drawbacks to using MEM protection of carbohydrates?

Like any chemical process, there are potential drawbacks to using MEM protection of carbohydrates. One issue is the potential for side reactions to occur, which can lead to low yields or unwanted products. Additionally, the removal of the MEM group may require harsh conditions, which can sometimes lead to the degradation of the desired product. However, with proper planning and execution, these drawbacks can be minimized and the benefits of MEM protection of carbohydrates can be fully utilized.

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