[AO8onBLK]

I am currently taking Organic II and need *delete me*

How can I turn Pentanal ... CH3CH2CH2CH2CH2(C=O)H into 5-bromo-pentanal

BrCH2CH2CH2CH2CH2(C=O)H.

I have tried NBS/Peroxide plus heat and just plain HBr, but my professor says this will not work!

What else will work!

Thanks in advance for your help.

[AO8onBLK]

Anyone?
 

[MissPhosgene]

Have you thought about radical reactions?

[Smrt guy]

Are you sure you have the right starting material?  Activating an unactivated C-H bond is not easy in general, and radical reactions favor more substituted carbons.  Nothing comes immediately to mind to do this; the 2-position would be far more active in general.

[MissPhosgene]

Are you sure you have the right starting material? 

That is a good point.

[orgopete]

This question asks us to guess what is being discussed in class. Okay, I am guessing enol chemistry. In order for that to work, you must convert the aldehyde into the unsaturated aldehyde by a bromination-dehydrobromination sequence. Then you can make a silyl enol ether, radical halogenation should give the more stable alkene, which I am guessing will place the bromine at the terminal position. Hydrolysis of the enol ether and catalytic reduction would give the product.

So, is the current topic enol chemistry?

[MissPhosgene]

Did you learn about radical reactions like the Barton reaction?