Abstract
The synthetic procedure for the preparation of DL-tryptophan, reported by Warner and Moe has been investigated. In the Michael-type condensation between acrolein and ethyl acetamidomalonate, a number of organic and inorganic basic substances were employed and their catalytic activity was studied. Anion exchange resins were found to be a convenient catalyst for the reaction. γ-Acetamido-γ, γ-dicarbethoxybutyraldehyde, a product of the above reaction, was obtained as phenylhydrazone, and the Fischer indole synthesis, that is, the conversion of the phenylhydrazone into ethyl α-acetamido-α-carbethoxy-β-(3-indole)-propionate, was successfully carried out by employing cation exchange resins as a catalyst. Subsequent hydrolysis and decarboxylation of the indole derivative gave DL-tryptophan in a good yield.
