It is proposed to study the biosynthesis of phenazine antibiotics. Shikimic acid has been found to be a precursor. The pairing scheme of 2 shikimic acid molecules has been investigated with C14 labeled precursors and is presently studied with C13 labeled precursors. The role of phenazine-1,6-dicarboxylic acid as immediate precursor of phenazine-1-carboxylic acid is studied. Various substituted dihydrobenzenes are synthesized to study their role as intermediates.