An efficient catalyst-free microwave (MW)-assisted method was elaborated for the batch and continuous flow synthesis of N-alkyl-isoindolinone phosphonates by the three-component reaction of 2-formylbenzoic acid, primary amines and various dialkyl phosphites. The reaction was also extended to various secondary phosphine oxides and primary amines, as well. In order to obtain more information about the condensation, the reaction mechanism was also studied by in situ FT-IR spectroscopy. [ABSTRACT FROM AUTHOR]