Methylidynetrisphosphonates: Promising C(1) building block for the design of phosphate mimetics

Methylidynetrisphosphonates are representatives of geminal polyphosphonates bearing three phosphonate (PO(3)H(2)) groups at the bridged carbon atom. Like well-known methylenebisphosphonates (BPs), they are characterized by a P–C–P backbone structure and are chemically stable mimetics of the endogenous metabolites, i.e., inorganic pyrophosphates (PP(i)). Because of its analogy to PP(i) and an ability to chelate metal ions, the 1,1,1-trisphosphonate structure is of great potential as a C(1) building block for the design of phosphate mimetics. The purpose of this review is to present a concise summary of the state of the art in trisphosphonate chemistry with particular emphasis on the synthesis, structure, reactions, and potential medicinal applications of these compounds.