Efficient and Green One-Pot Multi-Component Synthesis of α-Aminophosphonates Catalyzed by Zinc Triflate

Background: alpha-Aminophosphonates are an important class of compounds in medicinal chemistry with a wide range of biological effects. Despite the numerous synthetic methods for alpha-aminophosphonates reported in literature, there is still a need for the development of a simpler and greener protocol, for high throughput library synthesis. Objective: The primary objective of this work was to develop a simple, mild, eco-benign and low cost protocol, to obtain a wider variety of alpha-aminophosphonates for biological screening. Method: We report herein a simple and green methodology for the synthesis of alpha-aminophosphonates, in good yields, through the zinc triflate-catalyzed one-pot multi-component reaction of aldehydes, amines and dialkyl phosphites, at room temperature, under solvent-free conditions. Results: The one-pot three-component condensation of aldehydes, amines and dialkyl phosphites, performed at room temperature, under solvent-free conditions, in the presence of a catalytic amount of zinc triflate ( 10 mol%), gave the corresponding alpha-aminophosphonates in 72-93% yield. The present method was found to be tolerant toward various aldehydes, amines and dialkyl phosphites. A mechanistic rationalization for this reaction is also provided. Conclusion: We have successfully developed an efficient, green and straightforward methodology for the synthesis of alpha-aminophosphonates, through the zinc triflate-catalyzed one-pot multi-component reaction of aldehydes, amines and dialkyl phosphites, at room temperature, under solvent-free conditions. This synthetic strategy offers significant advantages such as good yields, versatile substituents, mild reaction conditions, easy workup and environmental safety, what make this protocol more amenable for high throughput library synthesis.