Formation and reaction of N-acyl- and N-methanesulfonyl-1-(3,4-dimethoxy)benzyl-7-acetoxy-1,2,3,4,6,7-hexahydro-7-methoxy-6-oxoisoquinolines (o-quinol acetates)

Oxidation of N-acyl- and N-methanesulfonyl-1,2,3,4-tetrahydro-7-methoxyisoquinolin-6-ols (7) with lead tetraacetate in dichloromethane produced quantitatively title compounds (o-QAs) (8). Treatment of N-trifluoroacetyl and N-formyl o-QAs (8a,b) with acetic acid at 30–40°C afforded N-trifluoroacetyl and N-formyl p-QAs (9a,b), while that of N-acetyl, N-ethoxycarbonyl and N-methanesulfonyl congeners (8c–e) gave N,N-dialkylacetamide (10c), ethyl N,N-dialkylcarbamate (10d), and N,N-dialkylmethanesulfonamide (10e), which are formed by elimination of a benzylic proton and subsequent cleavage of a C1–C8a bond in 9c–e.