An efficient method for the direct synthesis of substituted quinolines from anilines and aldehydes through C–H functionalization, C–C/C–N bond formation, and C–C bond cleavage has been developed. The method is simple and practical and employs air as an oxidant.
Metal-Free, Ionic Liquid-Mediated Synthesis of Functionalized Quinolines
作者:Jaideep B. Bharate、Sandip B. Bharate、Ram A. Vishwakarma
DOI:10.1021/co500047w
日期:2014.11.10
An expedient and metal-free synthetic protocol for construction of substituted quinolines has been developed from anilines and phenylacetaldehydes using imidazolium cation-based ionic liquids as the reaction medium. Mechanistic analysis indicated that the reaction occurs through C-C and C-N bond formation to produce isolable 2,3-disubstituted quinoline intermediates, which undergo C-C bond cleavage to produce 3-substituted quinolines. The reaction proceeds smoothly with a range of functionalities in good to excellent yields. Advantages of this protocol include metal-free, environmentally friendly, recyclable reaction media, higher yields and shorter reaction times, and thus is promising for the efficient combinatorial synthesis of structurally diverse 2,3-disubstituted and 3-substituted quinolines.