Highly Efficient Tetranuclear ZnII2LnIII2 Catalysts for the Friedel–Crafts Alkylation of Indoles and Nitrostyrenes

Abstract

Abstract:We demonstrate for the first time the high efficacy of tetranuclear Zn II 2 Ln III 2 coordination clusters (CCs) as catalysts for the Friedel-Crafts (FC) alkylation of indoles with a range of trans-β-nitrostyrenes. The reaction proceeds in good to excellent yields (76%-99%) at room temperature with catalyst loadings as low as 1.0 mol %.

2D‐2D Nanocomposite of MoS2‐Graphitic Carbon Nitride as Multifunctional Catalyst for Sustainable Synthesis of C3‐Functionalized Indoles

“…3‐(2‐Nitro‐1‐phenylethyl)‐1 H ‐indol‐5‐ol : 97 %; R f =0.50 (40:60 EtOAc/Hex); 1 H NMR (CDCl 3 , 500 MHz): δ =8.10 (brs, 1 H), 7.22–7.14 (m, 5 H), 7.04 (d, 1 H, J =8.2 Hz), 6.83 (d, 1 H, J =2.05 Hz), 6.79 (d, 1 H, J =2.05 Hz), 6.70 (dd, 1 H, J =2.75, 6.1 Hz), 5.87 (s, 1 H), 4.96 (t, 1 H, J =8.2 Hz), 4.88–4.84 (m, 1 H), 4.79–4.75 ppm (m, 1 H); 13 C NMR (CDCl 3 , 125 MHz): δ =149.4, 139.0, 131.5, 128.7, 127.6, 127.4, 126.6, 122.6, 113.3, 112.4, 112.1, 103.3, 79.2, 41.4 ppm.…”

Tetranuclear Zn2Ln2 coordination clusters as catalysts in the Petasis borono-Mannich multicomponent reaction

“…1) where Ln is Y (5Y), 40 Nd (5Nd), Gd (5Gd), Dy (5Dy), Tb (5Tb) and Yb (5Yb) retain their core intact in solution as conrmed by ESI-MS, EPR and NMR 15 and are highly efficient catalysts in two Friedel-Cras type reactions of indole; with aldehydes 15 and with substituted nitro-styrenes. 16 In both cases, the reactions proceed smoothly with as low as 1 mol% catalyst loadings, in environmentally friendly solvents, with excellent yields (80-100%) and with wide substrate scope. Having in mind that the Zn-Y/Ln metals are very close (3.3Å) in this specic topology and observing a chelation preference of aldehydes 15 to Y/Ln metals in 5, we envisioned that these catalysts would be an ideal synergistic template for the MCR reaction shown in Scheme 1.…”

“…8,9 So far, however, there are few examples of bimetallic 3d/4f CCs as efficient catalysts for water 10 or alcohol oxidation, 11 and our group has showcased the efficiency of isoskeletal 12 3d/4f CCs in domino electrocyclization 13,14 and Friedel-Cras alkylation reactions. 15,16 Multicomponent reactions (MCRs) dominate synthetic chemistry for the following reasons: they yield products from simple starting materials, in fewer steps, and in a shorter time when the reactions are carried out in a combinatorial way. [17][18][19][20][21][22][23][24][25][26][27][28] Among these transformations the Mannich-type condensation that involves amines, aldehydes and boronic acids, developed by Petasis, 29 known as the Petasis borono-Mannich (PBR) reaction has received considerable attention because it produces skeletons that can easily be converted to amino acids, heterocycles and alkylaminophenols.…”

Catalytic and conductivity studies in two dimensional coordination polymers built with a thiazole based ligand

“…Some of us have previously used a series of tetranuclear Zn2Ln2 coordination clusters as effective Lewis acid catalysts in Friedel-Crafts alkylation of indole with trans-β-nitrostyrene. [39] This reaction is poorly promoted by Zn(OTf)2 salt. In this work, given the polymeric nature of both compounds we examined their catalytic activity against the given alkylation reaction, aiming to develop an excellent heterogeneous as well re-usable methodology.…”