SO₃H‐functionalized ionic liquids catalyzed the synthesis of α‐aminophosphonates in aqueous media

Environmentally Benign Syntheses of α-Substituted Phosphonates: Preparation of α-Amino- and α-Hydroxyphosphonates in Water, in Ionic Liquids, and under­ Solvent-Free Conditions

“…as the counterion, and its application in the Kabachnik-Fields reaction. 48 In further studies, they decided to replace the relatively expensive imidazolium cat- ion in the ionic liquids by another, less expensive moiety, thus synthesizing α-aminophosphonates in the presence of sulfonic acid functionalized Bronsted acidic ionic liquid 5 bearing an alkane sulfonic acid group in an acyclic trialkylammonium cation (Table 11). 49 The ionic liquid 5 was entirely miscible with water and soluble in organic solvents.…”

A Critical Overview of the Kabachnik-Fields Reactions Utilizing Trialkyl Phosphites in Water as the Reaction Medium: A Study of the Benzaldehyde-Benzylamine Triethyl Phosphite/Diethyl Phosphite Models

“…It is a modification of the classical Kabachnik–Fields reaction, when the Shiff base (imine) is performed by the condensation of the aldehyde and the primary amine and the intermediate so formed is reacted with the dialkyl phosphite . There were attempts to accomplish the condensations under discussion in water medium . This, however, offers no specific advantage, as there is no need for solvent at all, and what is more, if water is used, a catalyst is also needed .…”

“…In another method, acyclic and cyclic quaternary onium salts (ionic liquids) were used as co‐solvents and at the same time as acid catalysts. The condensation of aromatic aldehydes, aromatic amines, and triethyl phosphite at room temperature gave the corresponding α‑aminophosphonates in yields of 89–96% in relatively short reaction times (10–60 min) (Table , entry 3) .…”

[BPy]HSO4 as an Efficient and Recyclable Catalyst for One-Pot Synthesis of α-Aminophosphonates under Solvent-Free Conditions

“…Thus, the development of simple, efficient, and environmentally friendly methods under mild conditions using recyclable catalysts for the synthesis of α-aminophosphonates is of current interest. Acidic ionic liquids have emerged as promising acid catalysts in replacement of conventional homogeneous and heterogeneous acidic catalysts because they are flexible, nonvolatile, noncorrosive, of low toxicity, immiscible with many organic solvents, and reusable [25] [27]) catalyzed synthesis of α-aminophosphonates has also been reported. Solvent-free organic reactions make procedures simpler and prevent solvent wastes, hazards, and toxicity [28].…”