Utility of Japp–Klingemann reaction for the preparation of 5-carboxy-6-chloroindole via Fischer indole protocol

5-Carboxy-6-chloroindole, a precursor for p38 kinase inhibitor, was prepared from 4-amino-2-chloro-3-iodobenzoicacid by following the Japp–Klingemann synthetic approach. The structures of the key intermediates were also confirmed by X-ray analyses. Computational analysis was helpful in understanding the importance of the substituents at the cyclization step of the synthesis.