Efficient Synthesis of 3,3‐diaryloxindoles Catalyzed by L‐prolinate Anion Immobilized onto Amberlite as a Novel Heterogeneous Organocatalyst

Abstract

L-prolinate anion immobilized onto amberlite IRA900OH ([Amb]L-Prolinate) is reported as a new, reusable and cheap organocatalyst for the condensation of indoles with isatins to afford the corresponding 3,3¢-diaryloxindol derivatives in ethanol under reflux condition.[Amb]L-Prolinate was achieved by the treatment of a MeOH/H 2 O solution of L-proline with amberlite IRA900OH at 60°C. The procedure for heterogenization of L-proline organocatalyst is based on non-covalent ion-pair immobilization of L-proline on the surface of anion-exchange resin amberlite IRA900OH (AmbIRA900OH) as a commercially accessible cationic polymer support. The prepared heterogeneous organocatalyst was well characterized by using of FTIR, TGA, DTG, XRD and elemental analysis techniques. The catalytic activity of the catalyst was also examined in the reaction of indole and isatin. The catalyst has been recovered and its reusability confirmed in 8 runs.

Non-Covalent Supported of l-Proline on Graphene Oxide/Fe3O4 Nanocomposite: A Novel, Highly Efficient and Superparamagnetically Separable Catalyst for the Synthesis of Bis-Pyrazole Derivatives

“…When considering the above mentioned argument, we recently introduced a new facile and cheap methodology for the preparation of l -prolinate-amberlite adduct by using ion-pair immobilization of l -proline on the surface of commercially available amberlite IRA-900OH as a heterogeneous and recoverable organocatalyst for the efficient synthesis of 2-amino-4 H -chromenes [ 27 ], spiroindoles [ 28 ], 3,3′-diaryloxindoles [ 29 ], bis-pyrazoles [ 30 ], 4 H -pyrano[2,3-c] pyrazole derivatives [ 31 ], and biscoumarin derivatives [ 32 ].…”

Silver molybdate (Ag‐PMo12) nanocomposite: An efficient catalyst for the one‐pot synthesis of 3,3‐diindolyl derivatives in aqueous medium

“…We have cited additional references within the Supporting Information [2e,4c,12,13,14–16] . The Supporting Information for this article contains the experimental section explaining all the experimental details along with general procedure, analytical and spectral data of all the synthesized compounds, and copies of their respective 1 H‐NMR and 13 C‐NMR spectra.…”

Chemistry of trisindolines: natural occurrence, synthesis and bioactivity

“…This was achieved by treating a 1 : 1 methanol/water solution of 0.01 M l -proline with amberlite IRA900OH at 60 °C for 6 h ( Scheme 16 ). 65 …”

“…Interestingly, the heterogeneous catalyst could be reused up to 8 times albeit with a slight 5% drop in the yield. 65 In addition, the catalyst is characterized by very low leaching of l -proline during 8 cycles. Another notable feature of this catalyst is its superiority compared to other catalysts in terms of yield and reaction times.…”