[Benzenelover]

I was looking at some organic structures to pass the time, and I noticed the structure of Phenylalanine was very similar to the structure of cinnamaldehyde. I was wondering, is it possible to use cinnamaldehyde as a sort of a backbone to synthesize phenylalanine? If so, which chiral position would it take, L, D, or a mixture of both?

I'm guessing the Cinnamaldehyde could be oxidized to cinnamic acid, which I heard happens fairly easily in air under heat, due to the reactivity of the aldehyde group. If somehow an amine group could be added to that second position where the double bond is held, I can see how it would be quite possible. The only questions I have are, is there a way to add that amine to the second position on the double bond? If so, which position will it take, L, or D? Will there be any dangerous side-reactions?

With this question, I turn to you guys. I'm sure with your infinite knowledge of chemistry, you'll have an answer.

[Honclbrif]

You are right that the two are related

http://en.wikipedia.org/wiki/Phenyl_propanoid

However, direct alpha-amination would be a bit of a pain. Is there another group you could easily install there which could be easily converted to an amine?

As for the stereochem: since you're stating with an achiral molecule you'll have to figure out a way to install the correct stereocenter yourself.

[Benzenelover]

I did consider a nitration followed by a hydrolysis to an amine, but I was worried the COOH group, or the aromatic ring might be more inclined to nitrate instead. As for the chirality, I suppose it could be flipped by an,Sn2 reaction, followed by an Sn1 reaction.

Edit: it just occured to me, maybe I could do a chlorination, followed by an Sn1 or Sn2.

[Honclbrif]

It can be tricky to get reliable monosubstitution when attacking halides with amines. Anything else they react with?

[Benzenelover]

I'm not too sure. Maybe a hydroxyl? I'm not too sure how well of a leaving group it would make, and how easily I could oxidize that position, but I know it would do a good job of snatching the extra hydrogen off of the amine. Maybe I'm looking at this wrong, though. Maybe I should be looking at catalysts, metalic or otherwise.

Edit: I was doing some reading online. It seems a substitution of a halide is entirely possible, as long as I have an excess of ammonia in solution.

[Proton]

Could you add across the double bond with HBr and then do an S_N2 with ammonia in ethanol? You would probably end up with a range of isomers though.

[orgopete]

It appears as though phenylalanine is prepared directly from cinnamic acid and ammonia by microorganisms, according to Wikipedia. As a chemist, I like the catalytic reduction of the acetamido-cinnamic acid to chiral acetylphenylalanine, and the Nobel Prize goes to William Knowles (McMurry, p 1027).

[Seanlet]

There is a route for direct amination of double-bonds called 'oxidative amination. You may have to protect the aldehyde with ethylene glycol first; it's just a thought. You can certainly add Br2 across the bond and halohydrin formation is quite possible.

Just ideas...