Syntheses of l‐β‐cyanoalanine‐4‐14C, l‐asparagine‐4‐14C, and l‐aspartic acid‐4‐14C

Syntheses are described from a common labeled intermediate of β‐cyanoalanine, asparagine, and aspartic acid, each of the l configuration and labeled with carbon‐14 in carbon‐four. Radiochemical purities were 96, 99.7, and 99 %. The common source of carbon‐14 was ethyl acetyl‐dl‐β‐cyanoalaninate‐4‐14C, which was prepared from commercially available potassium cyanide‐14C by an extension of the studies of Atkinson and Hellmann and Folz.