Synthesis of Complex Ureas with Brominated Heterocyclic Intermediates

Abstract

Herein we present an efficient method to synthesize novel complex ureas from simple ureas, with potential pharmacological activity. First, 3-methylindole ketones are protected via a two-phase N-tosylation reaction catalyzed by NBu 4 HSO 4 as the PTC. Second, an NBS bromination of the terminal methyl group is performed with high selectivity and very good yields. Finally, complex novel and promising ureas are synthesized in 46 %-92 % yields using non-base-catalyzed substitution reactions with simple monosubstituted and disubstituted ureas. All products were easily purified through column chromatography and/or crystallization. The overall procedure produces very high yields and selectivity for bromination.