Advantages of the Microwave Tool in Organophosphorus Syntheses

The microwave ( MW) technique has become an important tool also in the organophosphorus field of organic chemistry. On the one hand, otherwise reluctant reactions, such as the esterification of P-acids, may be enhanced by the effect of MW, while on the other hand, catalysts may be omitted, or catalyst systems may be simplified on MW irradiation. This later group includes the Kabachnik-Fields reactions, alkylation of active methylene-containing compounds, O-alkylations, de-oxygenations, as well as the Hirao reaction. It is also the purpose of this review to elucidate the scope and limitations of the MW tool, to interpret the MW effects, and to model the distribution of local overheatings and their beneficial effect. 1 Introduction 2 The Esterification of Phosphinic Acids 2.1 Synthetic Results 2.2 Scope and Limitation of the Application of MWs 2.3 Modelling the Distribution of the Local Overheatings and Predicting Their Effect 3 The Simplification of Catalytic Systems 3.1 Replacement of the Catalyst by MW Irradiation 3.1.1 The Kabachnik-Fields Reaction 3.1.2 Solid-Liquid Phase Alkylation of Active Methylene-Containing Compounds 3.1.3 Solid-Liquid Phase Alkylation of Phosphinic Acids 3.1.4 The Deoxygenation of Phosphine Oxides 3.2 The Hirao Reaction without Added P-Ligands 4 Conclusions