While the great preponderance of phosphate metabolites contain –O–P–O₃²⁻ bonds, there is a subset of ∼250 microbial and lower eukaryotic scaffolds with direct C–P bonds. Most have one C–P bond (–C–PO₃²⁻) and are classified as phosphonates. A much smaller number have two C–P bonds (–C–PO₂⁻C–) and are phosphinates. There appears to be only one enzyme-catalyzed route for conversion of C–O–PO₃²⁻ to C–PO₃²⁻ frameworks. Phosphoenolpyruvate (PEP) is converted by PEP mutase to phosphonopyruvate as the entryway to all known naturally occurring phosphonates. Phosphonopyruvate is then operated on by suites of enzymes that diversify the scaffold to various antimetabolites.