Brunner reaction

Oxindoles can be prepared from Af,p-acylphenylhydrazines by a reaction which is analogous to the Fischer cyclization. This is known as the Brunner reaction. The reaction is typically conducted under strongly basic conditions. For example, heating Af-phenylcyclopentanecarbonylhydrazide with CaO gives a 70% yield of spiro-cyclopentane oxindole[l]. 

A method was developed [185, 186] for the production of phosphorilated indolinones 172 by the cyclization of arylhydrazides of phosphorylated carboxylic acids. Depending on the conditions, the carboxylic acid arylhydrazides undergo cyclization to various products. Under the harsh conditions of the Brunner reaction (CaO, 200°C) 2-oxoindoles are formed under the mild conditions of the Kost reaction (POCI3, benzene, 80°C) 2-aminoindoles are formed [187],... 

Zttichr. f. anarg. Chemic 31, 151 (1002). Hoe also Brunner, Reaction Velocities in Heterogeneous Hystemn, p. 52. Thesis, Gottingen, 1903. Cf. mko Luther and Bruriee, Ztachr. f. phys, Chemie 45, 210 (1903). 

Replacement of =0 by CI2 or OH by Cl in the diacylamine function —CONHCO or —CON=C(OH)— also affords triazoles by analogy with the Einhorn-Brunner reaction (Scheme 72) (66AG(E)960, 76ZOR673). 

Einhorn-Brunner reaction. Formation of substituted 1,2,4-triazoles by condensation of hydrazines or semicarbazides with diacylamines in the presence of acid catalysts. 

This reaction was initially reported by Einhorn in 1905 and was extended by Brunner in 1914, therefore, it is known as the Einhorn-Brunner reaction. It is the synthesis of 1,2,4-triazoles by acid-catalyzed condensation between hydrazines (or semicarbazides) and diacylamines. It should be pointed out when two side chains in diacylamine are different, two isomeric triazoles will form. It was found that the substituent in the diacylamine derived from the stronger acid would appear in position 3 of the resulting triazole, indicating that the reaction is initiated by the attack of the free amino group of hydrazine on the more electrophilic carbonyl group of the stronger acid moiety. ... 

Other references related to the Einhorn-Brunner reaction are cited in the literature." ... 

This reaction is related to the Einhorn-Brunner Reaction. 

---