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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: some on March 23, 2006, 11:00:10 AM

Title: Oxidation of alfa,gamma-diols
Post by: some on March 23, 2006, 11:00:10 AM

Hello!

I need to oxidate 1,3-propanediol to hydroxyaldehyde? I tried cyclohexanone with Cp2ZrH2(cat.), 150', it didn't worked. Obviously monoprotection and selective oxidation is required. Could somebody give any suggestions about protecting group/oxidant?

Thank you.

Title: Re:Oxidation of alfa,gamma-diols
Post by: movies on March 23, 2006, 12:15:33 PM

A benzyl ether would be a good one.  It's easy to put on one hydroxyl selectively if you use NaH and 1 equiv of BnBr.  Then, you can oxidize the remaining alcohol with any of a number of oxidants, PCC for example.

Title: Re:Oxidation of alfa,gamma-diols
Post by: some on March 24, 2006, 08:57:22 AM

Thanks!

I already have it monoprotected with TBDMS. Do you think it can withstand PCC-oxidation?
 
::)

Title: Re:Oxidation of alfa,gamma-diols
Post by: movies on March 24, 2006, 12:21:16 PM

Yeah, that should be okay.  If you're really worried about it, there are plenty of other oxidation options: Swern, Dess-Martin, TPAP/NMO....

All of those would be fine with a TBDMS group.

In your case, there is the possibility of beta-elimination to form acrolein.  You might want to consider Dess-Martin reagent because it is probably the most mild oxidant of the ones that I mentioned, so beta-elimination would be minimized.