Journal of Organic Chemistry 2012-08-03

Protonated carbonic acid and reactive intermediates in the acidic decarboxylation of indolecarboxylic acids.

Adelle A Vandersteen, Scott O C Mundle, Ronald Kluger

Index: J. Org. Chem. 77(15) , 6505-9, (2012)

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Abstract

Elucidation of the mechanism for decarboxylation of indolecarboxylic acids over a wide range of solution acidity reveals the importance of protonated carbonic acid (PCA) as a reaction intermediate. In concentrated acid, the initial addition of water to the carboxyl group of the indolecarboxylic acid leads to a hydrated species that is capable of releasing PCA upon rate-determining carbon-carbon bond cleavage. The overall process is catalytic in water and acid, implicating PCA as a potential carboxylating reagent in the microscopic reverse reaction.