Chemoenzymic synthesis of N-(phosphonomethyl)glycine

Permeabilized, metabolically-inactive transformants of the methylotrophic yeasts Hansenula polymorpha and Pichia pastoris which contain significant quantities of the enzymes spinach glycolate oxidase ((S)-2-hydroxyacid oxidase, EC 1.1.3.15), Saccharomyces cerevisiae catalase T (EC 1.11.1.6), and endogenous catalase have been used as catalysts for the oxidation of glycolic acid by oxygen to produce glyoxylic acid in aqueous mixtures containing (aminomethyl)phosphonic acid. After separation and recovery of the microbial catalyst from the oxidation product mixture for reuse, the resulting solution of glyoxylic acid and (aminomethyl)phosphonic acid was subsequently hydrogenated with a palladium/carbon catalyst to produce N-(phosphonomethy)glycine (glyphosate), a broad-spectrum, postemergent herbicide. Complete conversion of (aminomethyl)phosphonic acid in the hydrogenation allowed the use of a simple acid precipitation for isolation of the N-(phosphonomethyl)glycine from the hydrogenation product mixture in high purity and yield.