Jourdan synthesis

JOURDAN-UIIMANN-GOLDBERG SYNTHESIS. Synthesis of substituted diphenylamines. The reaction products can be used as intermediates in the synthesis of acridones. 

When the synthesis of the appropriately substituted anthranilic acid cannot be achieved by the usual Jourdan-Ullmann method, the reaction of an aniline with diphenyliodonium carboxylate in the presence of... 

This reaction was first reported by Fischer and Jourdan in 1883. It is a synthesis of indole derivatives by the treatment of aryl hydrazones coupled from aromatic hydrazines and ketones or aldehydes with either a mineral or Lewis acid. Therefore, it is generally known as the Fischer indole synthesis. In addition, it is also referred to as Fischer cyclization, Fischer indole cyclization, Fischer indole reaction, Fischer indolization, Fischer reaction, and Fischer indole annulation. Although the mechanism has been extensively studied, the one formulated by Robinson and Robinson is now generally accepted. It involves the following steps (a) initial acid-catalyzed tautomerization of an aromatic hydrazone to an ene-hydrazine, b) a [3,3]-sigmatropic rearrangement of ene-hydrazine to a M-imine intermediate, (c) re-aromatization to aniline, d) intramolecular nucleophilic attack to form aminal, and (e) extrusion of an ammonia to afford the indole. 

---