Electrocatalytic cyclization of 3-(5-hydroxy-3-methylpyrazol-4-yl)-3-arylpropionitriles: 'one-pot' simple fast and efficient way to substituted spirocyclopropylpyrazolones

Electrolysis of 3-(5-hydroxy-3-methylpyrazol-4-yl)-3-arylpropionitriles in alcohol in an undivided cell in the presence of sodium bromide as mediator results in fast and efficient cyclization with the formation of the substituted spirocyclopropylpyrazolones in 60-90% substance yield. The fast (35 min) electrocatalytic reaction smoothly proceeds under neutral and mild conditions. The implication of electrocatalysis in cascade cyclization reaction is an efficient approach to medicinally relevant spirocyclopropylpyrazolones and is beneficial from the viewpoint of 'green chemistry' and diversity-oriented large-scale processes. (C) 2015 Elsevier Ltd. All rights reserved.