Metal complex-catalysed phenol coupling of phenolic benzylisoquinoline alkaloids

The proaporphine alkaloid glaziovine (1) was obtained by oxidative phenol coupling from N-methylcoclaurine (2) using tetraphenylporphyrinatomanganese(III) acetate (5) as the catalyst and sodium hypochlorite as the oxidant, or by non-oxidative phenolic coupling using N-methylcoclaurine-8-diazonium salt (8) as substrate and Ru3(CO)12 as the catalyst. Both reactions were performed under phase transfer catalysis (PTC). Two aporphine alkaloids (15) and (16) were obtained by oxidative phenol coupling using N-acetylreticuline (14) as substrate, dioxygen as the oxidant and bis(salicylaldehyde) ethylenediiminocobalt(II) (12) as the catalyst.