On the stereochemistry of the decarboxylation of (2S)-histidine catalysed by histidine decarboxylase from Clostridium welchii (E.C.4.1.1.22)

By decarboxylation of (2S)-histidine (1) in 2H2O in the presence of histidine decarboxylase from Clostridium welchii, monodeuteriated histamine (2a) was obtained. Ruthenium tetraoxide oxidation of (2a) furnished deuteriated β-alanine (3a), which was converted into the methyl ester of its phthaloyl derivative (6c). This compound showed a negative optical rotation, as did (6a) prepared from (3R)-(3c). From these results an (R)-configuration can be attributed to (2a) and consequently decarboxylation of (1) proceeds with retention of configuration.