Synthesis of Pyrido[3,2-b]carbazolequinones Involving N-Arylation of 5,8-Dimethoxy-6-nitroquinolines by Aryl Grignard Reagents and a New One-Pot, Palladium-Promoted Oxidative Coupling-Oxidative Demethylation Sequence
摘要:
The reaction between a 5,8-dimethyxy-6-nitrocarbostyril derivative and arylmagnesium bromides gave 6-arylaminocarbostyrils as the major products. Their subsequent treatment with palladium acetate in refluxing acetic acid gave linear pyrido[3,2-b]carbazolequinones in one step, involving the unprecedented oxidative demethylation of 1,4-dimethoxybenzene systems to the corresponding quinones by palladium acetate. A palladium-calalyzed oxidative functionalization of an unactivated C-H bond was also observed.