Synthesis of [1-13C] and [1-15N] labelled DL-homophenylalanine via a key Neber rearrangement

A synthetic route involving a key Neber rearrangement is described for the preparation of both [1-13C] and [1-15N] DL-homophenylalanine (2-amino-4-phenylbutanoic acid), using suitably labelled sodium cyanide as the source of the isotopic label. These compounds have been prepared for use in studies on the biosynthesis of phenylethyl glucosinolate in Brassica napus. 3-Phenylpropanaldoxime, the initial biosynthetic product formed from homophenylalanine, was also prepared in 15N labelled form.