Abstract:Formylphosphonate hydrate has been synthesised by the oxidation of diazomethylphosphonate with dimethyldioxirane (DMD) and its reactions, including the formation of imines, oximes, and Wittig olefination products, have been investigated. Formylphosphonate also acts as an efficient, selective formylating agent of secondary amines. β-Ketophosphonic acids derived from a range of amino acids have been prepared by the tin (II) chloride-catalysed reaction of diazomethylphosphonate with amino aldehydes and in certain cases shown to be potent inhibitors of leucine aminopeptidase.