the invention relates to a novel method for preparing pyrocatecholic compounds from monophenolic compounds using catalysis by monophenol monooxygenase in an aqueous solution containing metal ions . the metal ions form complexes with the pyrocatecholic products . this method increases the yield of pyrocatecholic products . in particular , the method of the instant invention can be used to increase the yield of l - dopa , a drug used in the treatment of parkinson &# 39 ; s disease .