Synthetic routes to Cleistopholine and methylated analogues

Abstract

Two synthetic pathways have been developed which lead to the natural product cleistopholine (1). One route has been adapted for the synthesis of the methylated analogues 2 and 3. The key step involved nickel-catalyzed regiospecific coupling of benzylic zinc bromides with methyl-2-bromo-4-methyl nicotinate (10) to afford benzylated pyridines followed by their subsequent transformations to the benzo[g]quinoline-5,10-diones.