General methods for the preparation of α and/OR β deuterium labelled 6‐hydroxydopamine derivatives

Abstract

AbstractA convenient synthetic method for the preparation of α and/or β deuterium‐labelled 6‐hydroxydopamines has been developed. Nitromethane was condensed with 2,4,5‐trimethoxybenzaldehyde to give 2,4,5‐trimethoxy‐α‐nitrostyrene (2). The nitroethylene side chain of 2 was reduced with sodium borodeuteride to afford β‐[2H]‐β‐(2,4,5‐trimethoxyphenyl)‐α‐nitroethane (3). A reduction with sodium borohydride in the presence of a deuterium source (e.g. EtOD) afforded mono and dideuterated α‐[2H]‐β‐ (2,4,5‐trimethoxyphenyl)‐α‐nitroethanes (9, 10). A reduction of the nitrostyrene 2 with sodium borodeuteride in EtOD resulted in the isolation of α,β‐[2H]‐β‐(2,4,5‐trimethoxyphenyl)‐α‐nitroethanes (15 and 16). Subsequent reduction of the deuterated α‐nitroethanes 3, 9, 10, 15 and 16 gave the appropriately labelled phenethylamine derivatives 5, 11, 12, 17 and 18. Removal of the phenol protecting groups afforded the deuterium labelled 2,4,5‐trihydroxyphenethylamines (6‐hydroxydopamines).