Organic Synthesis Question

[KCM92]

I have a quick question regarding glucose. If glucose (in pyranose form) is reacted with PBr₃ would it be possible to get only the primary alcohol to brominate? My thinking is that since it's much less hindered bromine will add much more quickly to the primary alcohol. Or would it be better to protect all of the alcohol groups, then selectively deprotect the primary alcohol? I'm asking because I need glucose with a bromine where the primary alcohol is located for a step in a synthesis project and am not very familiar with carbohydrate reactions. This is a small part of the overall project that I was unsure about. Also this is for an O-Chem II class just for reference.

 

Thanks for any advice.

 

Edit: Here's some more info

 

The final structure I need to make is below

 

Edited April 20, 2012 by KCM92

[Siddharth Yadav]

Hey KCM 92; if u still need help with the synthesis then let me know coz i have the synthesis of this compound!

[Dr. Lennox]

I have a quick question regarding glucose. If glucose (in pyranose form) is reacted with PBr₃ would it be possible to get only the primary alcohol to brominate? My thinking is that since it's much less hindered bromine will add much more quickly to the primary alcohol. Or would it be better to protect all of the alcohol groups, then selectively deprotect the primary alcohol? I'm asking because I need glucose with a bromine where the primary alcohol is located for a step in a synthesis project and am not very familiar with carbohydrate reactions. This is a small part of the overall project that I was unsure about. Also this is for an O-Chem II class just for reference.

 

Thanks for any advice.

 

Edit: Here's some more info

 

The final structure I need to make is below

 

 

Carbohydrate chemistry is an area of Organic Chemistry that requires extensive protective group manipulation in order to effect desired transformations. Your project involves two oxidations, a Horner-Emmons olefination and a Strecker amino acid synthesis. You'll be unable to do this without protective groups. Choose them wisely.

 

Good luck!