An Overview of the Synthesis of Phosphinates and Phosphinic Amides

The possibilities for the synthesis of phosphinic esters (phosphinates) and phosphinic amides, useful starting materials and intermediates, are discussed. The classical method involves the use of phosphinic chlorides in reaction with the alcohol/phenol or amine as the nucleophile. A greener approach may start from phosphinic acids, however, their direct esterification and amidation are not possible on conventional heating. According to a novel observation, the direct derivatizations (especially esterifications) still take place under microwave conditions. Another possibility is the alkylating esterification by alkyl halides to afford phosphinates. Phase transfer catalysis may be a useful tool to make such transformations possible. According to another strategy, the phosphinic acids are converted to more active intermediates that may then react with the O- and N-nucleophile efficiently. Among the activating agents, the T3P (R) reagent is the most noteworthy one. Among the other methods discussed, Arbuzov reaction and the fragmentation-related phosphinylations of O- and N-nucleophiles are underlined. It is interesting that there have not been real reviews in this field, although phosphinic starting materials and intermediates are utilized commonly in synthetic organic chemistry.