MOF-based Pd catalysts: a controllable and efficient platform towards cyclization reactions of isonitriles

Abstract

Catalytic efficiency is crucial to the reaction system and intrinsically related to the physical and chemical conditions. One of the challenges to enhance the catalytic efficiency has been the limited...

Heterogenized molecular Pd(ii) catalyst on ultrathin 2D metal–organic frameworks with nanoflower-like morphology for isonitrile-involved cyclization reaction

“…On the basis of these experimental results and previous works, 33,42 a plausible mechanism for the Zr-BTB-Bpy-Pd-catalyzed cyclization of isonitriles with N -acyl- o -alkynylanilines for 2-aminoquinolines was proposed (Scheme 2). Initially, the Pd( ii ) species of Zr-BTB-Bpy-Pd coordinates with 1a to generate intermediate I that can be confirmed by the results of FT-IR spectra of 1a /Zr-BTB-Bpy-Pd.…”

“…42 To improve the catalyst recyclability, a heterogeneous 3D MOF based Pd( ii ) catalyst Pd-UiO-67-Bpy was recently explored for the above reaction by our group. 33 Compared to the homogeneous Pd(OAc) 2 systems, in addition to markedly increased turnover numbers (TONs), the 3D MOF based Pd( ii ) catalyst exhibited better controllability of Pd( ii ) species in the catalytic process and the self-healing of the catalyst originated from the free uncoordinated Bpy moieties in the MOF. With the well-prepared Zr-BTB-Bpy-Pd in hand, herein we also evaluated its catalytic performance using the cyclization reaction of N -acyl- o -alkynylanilines with isonitriles.…”

“…The nanoflowerlike secondary structure of Zr-BTB-Bpy-Pd can enrich substrates and its ultrathin nanosheet petals can provide fully exposed Pd(II) active sites. As a proof of concept, an indepth comparison between Zr-BTB-Bpy-Pd and our recently reported 3D MOF based Pd(II) catalyst 33 as well as homogeneous Pd(OAc) 2 (ref. 42) were systematically evaluated through the Pd-catalyzed cyclization reaction of isonitriles with N-acyl-o-alkynylanilines.…”

“…Based on well-defined structure and excellent properties, MOFs provide a platform for indepth investigation of the structure-activity relationship of catalysts. 31 So far, a series of MOF-based Pd(II) catalysts have been reported for organic transformation reactions, 4,[32][33][34][35][36] in which the loading of Pd(II) active sites in MOFs can be usually achieved by three approaches: 1) MOF nodes containing Pd(II) ions; 37 2) the functional organic linkers in MOFs anchoring Pd(II) ions; 4,32,33,38 and 3) the pore space in MOFs accommodating Pd(II) active species. 35 However, owing to most of the active sites being located inside the large-sized three-dimensional (3D) MOF frameworks, the accessibility of substrates, especially large-size substrates, is restricted kinetically, which not only decreases the utilization of Pd atoms, but also reduces the catalytic efficiency.…”

Metalation of metal–organic frameworks: fundamentals and applications

“…Meanwhile, the potential metal sites could be well reserved without being occupied in solvothermal reactions. [108][109][110][111][112][113][114] Fig. 6 shows some of the typical organic ligands used for constructing MOFs for metalation.…”