[SynthesisIsFun]

Hi everyone! I am trying to work out a synthesis for a novel compound. Is there a way to remove benyzl protective groups from aliphatic amines by catalytic hydrogenation without harming (unprotected) alkyne functionalities which are also present in the molecule?

Many thanks for you *delete me*

[sjb]

Hi everyone! I am trying to work out a synthesis for a novel compound. Is there a way to remove benyzl protective groups from aliphatic amines by catalytic hydrogenation without harming (unprotected) alkyne functionalities which are also present in the molecule?

Many thanks for you *delete me*

I don't know if you can protect these with a Pauson-Khand type intermediate or similar, I suspect not (though perhaps http://preview.tinyurl.com/alkyneprotect
 helps). Do you have to use a benzyl protecting group? Perhaps switch for a PMB amine which you may be able to oxidize (rather than reduce) off - depends on your other functionalities, I guess.

[orgopete]

Is there a way to remove benyzl protective groups from aliphatic amines by catalytic hydrogenation without harming (unprotected) alkyne functionalities which are also present in the molecule?

This is like asking if you can reverse the order of reactivity or can you may HOAc more acidic than HCl? That would be difficult. What is more plausible is to find reactions in which the reactivity order is favorable for your objectives. I'm sure there are protecting groups that can be removed in the presence of acetylenes. Whether their chemistry is compatible with other functionality and objectives is another question.

[willug]

I've been doing a bit with those cobalt alkyne complexes recently. If you have some dicobalt octacarbonyl it is a very easy reaction to try. Just stir the alkyne and Co2CO8 together in DCM untill no more CO is evolved (my substrate took all of about 5 minutes) then filter though a short plug of silica. Only problems are that it's a little bit expensive and highly toxic. I guess it might offer some protection against hydrogenation if you didn't force it, but like sjb I'm not really sure...

[PhDoc]

Take a look in Greene's Protective Groups in Organic Synthesis. I remember benzylamines as not being much fun to remove. Best protective groups for amines if functionally compatible are carbamates such as Boc or Cbz.

http://www.amazon.com/Greenes-Protective-Groups-Organic-Synthesis/dp/0471697540

[discodermolide]

Hi everyone! I am trying to work out a synthesis for a novel compound. Is there a way to remove benyzl protective groups from aliphatic amines by catalytic hydrogenation without harming (unprotected) alkyne functionalities which are also present in the molecule?

Many thanks for you *delete me*

You won't get the benzyl group off in the presence of the acetylene  using hydrogenation, the acetylene is more reactive.
As sub suggested use a different amine protection.