Quite cool, old route to Tryptophan

[pHarmacist]

LOL!, I know, this is from the 'forties' and it's about tryptophan, but concept is cool; as you probably know, gramine and, especially, its quaternary salts are very useful synthetic intermediates as they are easily prepared and the dimethylamino function is easily displaced by nucleophiles. To illustrate this, I supply you with this article where they use acetamidomalonate anion as a nucleophile to eventually end up with tryptophan from gramine in 80% yield. Interesting IMO!  

Here you go:

The Application of a New Alkylation Reaction to the Synthesis of Tryptophan
 
E. E. Howe, A. J. Zambito, H. R. Snyder, M. Tishler;
J. Am. Chem. Soc.; 1945; 67(1); 38-39.
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Full Text:

http://pharmacist8.tripod.com/coololdtryptophan.pdf