A facile synthesis of 4-, 5- and 6-chloromethyl-1H-indole-2-carboxylates: replacement of a sulfonic acid functionality by chlorine

Valuable new synthetic intermediates, 4-, 5- or 6-chloromethyl-1H-indole-2-carboxylates, were prepared by the facile elimination of SO2 from 2-ethoxycarbonyl-1H-indole-4-, 5- or 6-methanesulfonic acids, respectively, easily accessible by Fischer-type indolization.