6,7-Dihydroxy-1,2,3,4-tetrahydroisoquinoline formation by iron mediated dopamine oxidation: A novel route to endogenous neurotoxins under oxidative stress conditions

Article abstract of DOI:10.1016/S0040-4039(99)00272-5

Aerobic oxidation of dopamine mediated by iron ions gives 6,7- dihydroxy-1,2,3,4-tetrahydroisoquinoline (2) and 3,4-dihydroxybenzaldehyde (4) in yields up to 10% and 15%, respectively. Based on ¹³C labelling experiments, a reaction mechanism is proposed involving oxidative fission of the dopamine side chain to give 4 and formaldehyde, the latter giving 2 by Pictet-Spengler condensation with dopamine. This provides a novel route to endogenous generation of neurotoxic isoquinoline alkaloids under oxidative stress conditions.