Expedient routes to valuable bromo-5,6-dimethoxyindole building blocks

The synthesis of 3-, 4-, 7-bromo and 4,7-dibrominated 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) derivatives is reported. Hemetsberger and Bartoli indole syntheses were investigated and expedient routes to the desired compounds were developed. These indoles are valuable substrates for elaboration using transition metal-mediated cross-coupling chemistry. (C) 2008 Elsevier Ltd. All rights reserved.