Synthesis and spectroscopic characterization of protected N-phosphonomethylglycine dipeptides

A series of terminally blocked dipeptides containing C-terminal N-phosphono methylglycine (glyphosate, an extremely effective non-selective post-emerge nce herbicide) have been synthesized by a solution method. The presence of their two conformers, cis (syn) and trans (anti), was shown in solutions by NMR spectroscopy. Molecular structures of the peptides were also determine d in the solid state by X-ray diffraction. The attempts for the selective a nd total removal of the groups protecting amino, carboxylic and phosphonate functions were in many cases unsuccessful due to the formation of cyclic s tructures and breakage of the phosphorus-to-carbon bond. Copyright (C) 2001 European Peptide Society and John Wiley & Sons, Ltd.