Topic: Selective hydrogenation C=N Vs. C=O (Read 5589 times)

taurean · « **on:** January 05, 2008, 05:53:39 PM »

Is there any hydrogenation catalyst which would selectively hydrogenate C=N in the presence of C=O?

Please let me know.

Kryolith · « **Reply #1 on:** January 05, 2008, 06:01:36 PM »

I don't know a catalyst by heart, but why don't you just protect the carbonyl group?

Fry · « **Reply #2 on:** January 05, 2008, 06:09:31 PM »

what about a weaker hydride agent like sodium cyanoborohydride?

ultrashogun · « **Reply #3 on:** January 05, 2008, 06:38:12 PM »

what about a weaker hydride agent like sodium cyanoborohydride?

This is good if you want to make a ketone to an immine and then directly reduce the immine all in one step.

Fry · « **Reply #4 on:** January 05, 2008, 06:40:34 PM »

No good for neutral imines?

Ah okay

sjb · « **Reply #5 on:** January 06, 2008, 05:49:20 AM »

No good for neutral imines?

The mere fact that you *can* do reductive amination by throwing carbonyl, amine and cyanoborohydride (or acetoxyborohydride, if you're worried about the cyanide, though I think in some cases this is less effective) with little alcohol byproduct suggests it may be reasonably selective.

Have a look though Abdel-Magid et al at http://dx.doi.org/10.1021/jo960057x via http://www.organic-chemistry.org/chemicals/reductions/sodiumtriacetoxyborohydride.shtm

S

taurean · « **Reply #6 on:** January 06, 2008, 04:56:40 PM »

Thanks guys for the suggestions. I will give a try.