Lewis Acid-Directed Cyclocondensation of Piperidone Enol Ethers with 2-Methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine: A New Regioselective Synthesis of Oxygenated Carbolines
摘要:
Lewis acid-directed cyclocondensations of piperidone enol ethers with 2-methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine are reported. Benzofurans are obtained with BF3. OEt2 as a promoter, whereas use of excess amounts of TiCl4:Ti(OiPr)(4) leads to tetrahydrocarbolines. The latter reactions provide expedient routes to oxygen-substituted tetrahydrocarbolines and carbolines. As applications of this new methodology, the preparations of 1-[3-(dimethylamino)propyl] amino-7-methoxy- and 1-[3-(dimethylamino)propyl]amino-7,8-dimethoxy-5H-pyrido[4,3-b]indoles are described.
Lewis Acid-Directed Cyclocondensation of Piperidone Enol Ethers with 2-Methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine: A New Regioselective Synthesis of Oxygenated Carbolines
摘要:
Lewis acid-directed cyclocondensations of piperidone enol ethers with 2-methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine are reported. Benzofurans are obtained with BF3. OEt2 as a promoter, whereas use of excess amounts of TiCl4:Ti(OiPr)(4) leads to tetrahydrocarbolines. The latter reactions provide expedient routes to oxygen-substituted tetrahydrocarbolines and carbolines. As applications of this new methodology, the preparations of 1-[3-(dimethylamino)propyl] amino-7-methoxy- and 1-[3-(dimethylamino)propyl]amino-7,8-dimethoxy-5H-pyrido[4,3-b]indoles are described.
Lewis Acid-Directed Reactions of Benzoquinone Mono-/Bis-imines: Application to Syntheses of Substituted β- and γ-Tetrahydrocarbolines
作者:Thomas A Engler、Jutta Wanner
DOI:10.1016/s0040-4039(97)01391-9
日期:1997.9
Ti(IV)-promoted reactions of N-phenylsulfonyl-3- and 4-piperidone enol ethers with 2-alkoxy-4-(N-phenylsulfonyl)imino-1,4-benzoquinone afford 8-alkoxy-7-hydroxy-tetrahydrocarbolines. However, reactions promoted by BF3 produce substituted benzofurans. Ti(IV)- or BF3-promoted reactions of 2-alkoxy-1-(N-benzoyl)-4-(N-phenylsulfonyl)-1,4-benzoquinone bisimines also afford substituted tetrahydrocarboline