Chapter 6: Synthesis of Phosphonic Acids and Their Esters as Possible Substrates for Reticular Chemistry

The scope of this chapter is to describe selected group of methods of synthesis of phosphonic acids and their esters which have found use or seems of interest in metal phosphonate chemistry. In the first place some properties of phosphonic group are mentioned. Those are geometry, acidity, and coordination of phosphonic group compared to carboxylic group, as the most frequently used organic group in synthesis of coordination polymers. In the main part of the chapter most popular synthetic methods leading to phosphonic acids and their esters are reviewed. Three fundamental methods are the Michaelis–Arbuzov reaction, catalytic cross-coupling reaction, and the Mannich-type condensation. These methods are presented in terms of substrate and reagent description, reaction scheme and mechanism, examples and a selected procedure Additionally number of other useful reactions leading to P–C bond formation are briefly described. If synthesis leads to an ester, transformation into a phosphonic acid is usually required. Therefore, two methods of such transformation are presented: acidic hydrolysis and transsilylation/methanolysis. This subsection consists of a description with a scheme of reaction. Some spectral characterization of obtained ligands are also considered. The final part of the chapter includes concluding remarks based on a statistical analysis of the use of the described synthetic methods in the past five years.