Ultrafast synthesis of α-aminophosphonates using ternary deep eutectic solvent in water

A remarkably rapid synthesis of α-aminophosphonate medicinally privileged scaffold is developed using a ternary deep eutectic solvent (TDES) of urea/SnCl₂/HCl catalyst. Newly promoted TDES enabled a sustainable pathway to a library of the desired compounds with divergent electronic and steric characteristics simply using water as the solvent. The TDES-promoted protocol boasts unusual reaction times of 48-120 s, particularly for a batch chemistry process of organic synthesis, selectively churning out quantitative yields of a range of α-aminophosphonates. The catalyst entails total atom economy in its synthesis, and with a kinematic viscosity of 2.68 mm².s^-1, it is freely flowing at room temperature, making it a worthwhile candidate for utilization in large-scale process chemistry. The protocol is amenable to scaled-up synthesis as the use of the stable catalyst enabled its retrieval and reuse in at least three successive runs. ¹¹⁹Sn-NMR and¹³C-NMR spectroscopy techniques were employed to fully characterize the TDES catalyst produced from cheap, abundant chemicals. Additionally, UV-VIS analysis was adopted for monitoring the extraordinarily swift synthetic procedure, and stereochemical assignment analysis was implemented for α-aminophosphonate products using NMR spectroscopy, highlighting the synthetic selectivity of the process.