Vilsmeier and Haack'discovered that secondary and tertiary aromatic amines can be converted into aldehydo derivatives by the action of N-methylformanilide and phosphorus oxychloride, a reaction reminiscent of the Bischler-Napieralski synthesis of isoquinolines. In a series of patents, Kalischer, Scheyer and Keller2 reported that the reaction is applicable to certain phenol ethers and aromatic hydrocarbons, and these claims were verified by ...
