[11C]octopamine synthesis using [11C]cyanide: chemical and enzymatic approaches for the [11C]cyanohydrin synthesis.

Abstract [ 11 C]- p - and m -octopamine hydrochloride were synthesized from [ 11 C]HCN in a two-step sequence. Chemical and enzymatic approaches were used for the formation of the [ 11 C]cyanohydrin intermediates as the key step. Isolated radiochemical yields of 0.7–2.3% at the end-of-synthesis were obtained with an overall preparation time of 40–60 min. The enantiomeric purity of the [ 11 C]- p -octopamine obtained through the enzymatic process was 92% e.e. in the ( S )-enantiomer, whereas that of the [ 11 C]- m -octopamine was 42% e.e. in the ( R )-enantiomer, as determined by HPLC without any derivatization.