Facile InCl3-catalyzed room temperature synthesis and electrochemical behavior of ferrocene appended (R, S)-α-aminophosphonates

Abstract

α-Aminophosphonates represent a significant category of the phosphorus family. Due to the additional ‘N’ atom(s), these compounds exhibit interesting electronic, coordination, and electrochemical properties. In this regard, the present work is focused on the In(III)-catalyzed synthesis of new ferrocene-appended α-aminophosphonates using the well-known Kabachnik−Fields reaction. Notably, all the reactions proceed to complete at room temperature in ethanol to provide the products with excellent yields in the range of 87–95%. The reaction proceeded smoothly with a broader substrate scope containing -Cl, Br, F, NO2, t‑butyl, and 3,5-dimethyl substituents at various positions. The purity of the products was assessed by analytical and spectroscopic techniques including 1H, 13C and 31P NMR along with HR-MS spectroscopic analysis. Among 18 compounds, 17 derivatives were crystallized in triclinic and monoclinic systems with P-1, P21/n, or P21/c space groups. From the results, the length of P = O bonds exhibits a range spanning from 1.447(2) Å (4c) to 1.469(2) Å (4l). Additionally, the electrochemical studies of all the synthesized compounds showed an effective redox response. The presence of the phosphoryl group and the substituents have a distinct influence on the electrochemical behavior of the synthesized molecules.