The massive commercial success of glyphosayte as herbicide and the fact that is resilient to raised temperatures, oxidising agents, reducing agents, and acidic and basic conditions means that a very wide variety of methods for the synthesis, of glyphosate and its derivatives, have been developed over the past twenty plus years, since its discovery. Variations on the classical 'Mannich' process are the most widely reported methods in the formation of the glyphosate backbone (ie.the P-C-N linkage).
I have categorised the very broad range of syntheses of glyphosate into four broad categories, which are as follows: