Acid-Catalysed Condensation of Indole with Acetone

1% Acid-Catalysed Condensation of Indole with Acetone 

The hydrochloric acid-catalysed condensation of indole with acetone has been a topic of occasional study for almost a century. A complex mixture of products is obtained, but using modem separation, analytical and spectroscopic techniques it is now possible to assign structures unambiguously. The latest compound to be identified is 1. 

Suggest a mechanism to account for the formation of 1 from indole and acetone. 

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