A Facile Route to 1,3-Diazaheterocycle-Fused [1,2-a]Indole Derivatives via Acetic Acid Catalyzed Cyclocondensation Reactions

A concise and efficient route for the synthesis of 1,3-diazaheterocycle-fused [1,2-a]indoles by simply refluxing a reaction mixture of different types of heterocyclic ketene aminals and 1,4-benzoquinones catalyzed by acetic acid was developed. This protocol provides an alternative method for application in combinatorial and parallel synthesis in drug discovery.