Synthesis of Antitumor Benzophenanthridine Alkaloids and Related Compounds

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1,Regioselective synthesis of 2,3,9,10-oxygenated protoberbering alkaloids was developed starting from readily available benzaldehydes and phenethyl amines.2.2,3,9,10-oxygenated protoberbering were converted to2,3,10,11-oxygenated protoberberines through C_8-C_<8a> bond cleavage followed by photo-cyclization.3.Biomimetic and efficient conversion of berbering to chelerythrine was achieved through regioselective C_6-N bond cleavage,acetalization with thallium trinitrate, and then acidic cyclization.Fagaridine was synthesized from berberine via oxychelerythrine through selective demethylation.4.The above synthetic method was applied to a convevient synthesis of antitumor alkaloids,nitidine and fagaronine.5.This synthetic method was further confirmed tobe a general method for a synthesis of fully aromatized benzophenanthridine alkaloids by a synthesis of oxyterihanine and sanguilutine.6.Chelidonine and chelamine were stereoselectively synthesized from coptisine through cationic cyclization,that established the stereochemistry of chelamine. Similarly,berbering was converted to homochelidonine and chelamidine.7.The present synthesis provides a novel synthesis of both B/C-hexahybro-and fully aromatized benzophenanthridine alkaloids via common intermediates,which gave also sanguinarine and chelerythrine.