A versatile new synthesis of quinolines and related fused pyridines. Part 8. Conversion of anilides into 3-substituted quinolines and into quinoxalines
3-substituted quinolines (7). When N-nitrosodialkylamines are used in place of dimethylformamide as the Vilsmeier agent, the anilides are converted into 2-chloroquinoxalines in low yields. Several by-products are formed and the mechanisms have been explored. Thus, the formation of ethyl N-arylcabamate from the corresponding propionanilide is shown to involve an C→O alkyl migration related to a Wolff rearrangement
triplet‐sensitized di‐π‐methane rearrangement reaction to the corresponding 3‐cyclopropylquinolones upon irradiation with visible light (λ=420 nm). A chiral hydrogen‐bonding sensitizer (10 mol %) was shown to promote the reaction enantioselectively (88–96 % yield, 32–55 % ee). Surprisingly, it was found that the enantiodifferentiation does not occur at the state of initial product formation but that it is the result