Synthesis of 4-Difluoromethylquinolines by NHC-Catalyzed Umpolung of Imines
摘要:
The N-heterocyclic carbene (NHC)-catalyzed umpolung of aldimines for the synthesis of 4-difluoromethyl-quinoline derivatives is reported. In the presence of NHCs, the intramolecular cyclization of aldimines bearing a moderately electron-poor double bond due to the presence of the -CF3 group likely proceeds via the intermediacy of the aza-Breslow intermediate. The key to the success of this aza-Stetter type transformation is the NHC generated from the bicyclic triazolium salt using DBU as the base.
4-Difluoromethylated Quinoline Synthesis via Intramolecular S<sub>N</sub>2′ Reaction of α-Trifluoromethylstyrenes Bearing Imine Moieties
作者:Takashi Mori、Junji Ichikawa
DOI:10.1246/cl.2004.1206
日期:2004.9
Intramolecular cyclization of o-methyleneamino-substituted α-trifluoromethylstyrenes is promoted by DBU and a catalytic amount of KCN to provide 4-(difluoromethyl)quinolines. The reaction proceeds ...