Activation of iodosobenzene by catalytic tetrabutylammonium iodide and its application in the oxidation of some isoquinoline alkaloids

摘要: Oxidation of N-methyltetrahydroisoquinolines with iodosylbenzene in the presence a catalytic amount tetrabutylammonium iodide various solvents afforded N-methyl-2H-3,4-dihydroisoquinol-1-ones almost quantitative yields. The application this finding to oxidation other isoquinolines, including tetrahydroisoquinolines, lycorine diacetate, and benzyltetrahydroisoquinolines, also corresponding lactams good yields, however, accompanied by few minor byproducts. Under similar conditions, tetrahydroberberine gave rearranged compound, berberal, as major product, 8-oxoberberine berberine.