Studies On The Reductive Cyclization Of 2-Nitrochalcones With Methyl Isocyanides

Nitrogen-containing heterocyclic compounds as large kinds of organic compounds having diverse structures,widely found in bioactive natural products,drug molecules and organic functional materials,such as vitamins,alkaloids,pigments and spices etc.Among them,N-oxide compounds with great potential value are not only exists in many natural products,drugs and chemical products,but also could act as chiral ligands of many natural and pharmacological components,play an indispensable role in chemistry,biology and material science.2-Nitrochalcone compounds can be prepared by aldol reaction,as important organic synthetic intermediates which are easily synthesized and have many reaction sites,often used in synthesis of variety of aza-heterocycles.In general,2-nitrochalcone often used in synthesis corresponding quinoline N-oxide through reductive cyclization catalyzed by reductant.This thesis introduces an external reductant-free method for the synthesis of pyrrolo[3,4-c]quinoline N-oxides from 2-nitrochalcone and active methylene isonitrile.The process include two steps:firstly,generate dihydropyrrole compounds in[3+2]cycloaddition reaction from 2-nitrochalcone and methylene isonitrile under Ag₂CO₃ catalyzed.Then,under base and heating conditions,dihydropyrrole used as an in situ generated internal reductant to convert nitro into nitroso group,and nitroso in reducing solvents can be further reduced to hydroxylamine compounds,and C-N bond was formed to construct pyrrolo[3,4-c]quinoline N-oxides through intramolecular nucleophile addition reaction.This high efficient synthesis method of pyrrolo[3,4-c]quinoline N-oxides from the simple,easily available and inexpensive materials,and the more important is the reductive cyclization proceed in an external reductant free condition.