Formation of Enehydrazine Intermediates through Coupling of Phenylhydrazines with Vinyl Halides: Entry into the Fischer Indole Synthesis

摘要

Indoles, one of the most abundant heterocycles in nature, constitute the essential functional cores in the structures of various fragrances, dyes, agricultural chemicals, and pharmaceuticals. The synthesis of indoles has been an active research field because of their structural diversity as well as the numerous applications of natural and synthetic indole derivatives. Over the last century, a wide array of approaches have been developed, and among them the Fischer indole synthesis is probably the most well-known method because of its fascinating combination of experimental simplicity and mechanistic complexity. Although it was established over a century ago in 1883, the Fischer indole synthesis still remains a popular research topic and substantial efforts have been made to explore its applications or to overcome its drawbacks.