AbstractWith the publication of this work, all six theoretically possible isomers of DL‐diaza‐phenylalanines have now been reported. 2‐Pyrazinyl‐ (VII), 3‐pyridazinyl‐ (VIII), 4‐pyridazinyl‐ (IX), 4‐pyrimidinyl‐ (X), and 2‐pyrimidinylalanine (XI) were synthesized by the catalytic (in the cases of VII‐X) or stannous chloride (in the case of XI) reduction of the corresponding (α‐oximino‐β‐(diazaphenyl)propionic acids. These compounds were in turn prepared by the Claisen condensation of appropriate methyldiazines with diethyl oxalate followed by treatment of the resulting pyruvic ester with hydroxylamine.Condensation of 5‐bromomethylpyrimidine with diethyl N‐ carbobenzoxyaminomalonate yielded diethyl N‐carbobenzoxyarmno‐(5‐pyrimidinylmethyl)malonate. Hydrolysis and debenzylation of the condensation product readily g