Cu(II)–Hydromagnesite Catalyzed Synthesis of Tetrasubstituted Propargylamines and Pyrrolo[1,2-a]quinolines via KA2, A3 Couplings and Their Decarboxylative Versions

Abstract

A novel copper supported on hydromagnesite (Cu/HM) nanomaterial was prepared by a simple impregnation method at room temperature and characterized by PXRD, SEM, TEM, EDAX, XPS, ICP-AES and FT-IR techniques. The EDAX and XPS results revealed the presence of 8.82 wt % of copper in (+2) oxidation state. Three-component coupling of ketone and amine with alkyne to afford tetrasubstituted propargylamine is known as KA2 coupling, whereas the three-component reaction of aldehydes and amine with alkyne to give propargylamine is considered as an A3-coupling reaction. The Cu/HM was found to be an efficient heterogeneous catalyst for KA2 coupling reaction under solvent free condition, and A3 coupling strategy to afford the pyrrolo­[1,2-a]­quinolines in DEG as a green solvent. The high catalytic activity of Cu/HM in the A3 coupling strategy to afford propargylamine intermediate is due to the synergistic effect of both Cu2+ and Mg2+ active sites. The versatility of Cu/HM catalyst was also studied for the decarboxylative A3 and KA2 coupling strategies. The present method offers several advantages such as simple procedure for the catalyst preparation, versatile catalytic applications, cheap precursors, higher yield of products in short reaction time, recovery and reusability of the catalyst.

CuII@PAA/PVC mesoporous fibers: A hybrid wedding as a high‐performance versatile heterogeneous catalyst for A3, KA2, and decarboxylative A3 reactions

“…As shown in Figure , the binding energies of Cu 2p in the fresh (Figure a) and recovered catalyst (Figure b) were measured to be 932.8 eV and 953.1 eV. These results indicated that the presence of Cu II species in both freshly prepared and recovered catalyst …”

“…These results indicated that the presence of Cu II species in both freshly prepared and recovered catalyst. [19][20][21]44] The SEM images of PAA/PVC and Cu II @PAA/PVC shown in Figure 4 were recorded at low (200 nm) and high magnifications (100 nm) for easy clarity and comparison. The visible rough surface with porous can be observed for PAA/PVC hybrid fibers (image a, and b).…”

“…Thus, the development of facile and efficient heterogeneous catalysts for the A 3 reactions still continues to be in strong demand. As heterogeneous catalysts, supported Cu catalyst (MCM‐TSCuI, Cu/HM, CMC‐Cu II , and Cu 0 @HAP@γ‐Fe 2 O 3 ), copper‐based MOF (Cu‐MOF‐74, and Cu‐MOFs), supported Ag (γ‐Fe 2 O 3 @SiO 2 /g‐C 3 N 4 /Ag, and AgI‐K10), core‐shell Au@MOF‐5, Au NPs‐Fe 3 O 4 ‐rGO, and so on, were successfully employed to catalyze A 3 coupling reactions. Meanwhile, to gain more diverse polysubstituted propargylamines, another variant of A 3 coupling, i.e.…”

“…In the decarboxylative A 3 couplings, alkynyl carboxylic acids act as economical and stable surrogate for terminal alkynes via extrusion of CO 2 in situ. Thus, a number of homogeneous catalysts such as CuI, CuBr, CuCl 2 /CuI, CuI/Cu(OTf) 2 , and heterogeneous catalysts including Cu(II)/HM, CuO/Fe 2 O 3 NPs, Cu@SiO 2 ‐NS, and chit@copper have been used in decarboxylative A 3 coupling reactions.…”

An efficient and environmentally sustainable domino protocol for the synthesis of structurally diverse spiroannulated pyrimidophenazines using erbium doped TiO2 nanoparticles as a recyclable and reusable heterogeneous acid catalyst

“…Multicomponent reactions (MCRs) catalyzed by heterogeneous catalysts offer a green and sustainable strategy with high atom economy and low environmental factor (Efactor) due to the involvement of fewer reaction steps, simple workup, easy recovery, and reusability of the catalyst without isolation of intermediates. [1][2][3][4][5] Moreover, multicomponent reactions provide easy and rapid access to large libraries of drug-like scaffolds incorporating medicinally privileged heterocyclic substructures. 6,7 The nanostructured materials have attracted the attention of chemical research in view of their uses as heterogeneous catalysts in organic transformations, especially because they following the requirements of green chemistry.…”