Vilsmeier–Haack reactions of α-hydroxyketenedithioacetals: a facile synthesis of substituted pyridines

✍ Scribed by Ajith Dain Thomas; C.V Asokan

• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 57 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)00174-0

✦ Synopsis

The reaction of a-hydroxyketenedithioacetals, generated by the 1,2-addition of methyl Grignard reagent to aoxoketenedithioacetals, with the Vilsmeier reagent was investigated. The reaction proceeds with acid-catalysed dehydration to afford sulphur substituted 1,3-butadienes, which undergo subsequent iminoalkylations. The intermediate iminium salts formed were successfully transformed into 2-methylsulfanyl substituted 4-aryl pyridines, in the presence of ammonium acetate