H3PW12O40/SBA-15 for the Solventless Synthesis of 3-Substituted Indoles

A family of silica-supported H3PW12O40 (HPW) solid acid catalysts was prepared by wet impregnation of mesoporous SBA-15 and investigated for the solventless synthesis of 3-substituted indoles under mild conditions. Mesoporous SBA-15 facilitated a high dispersion of immobilised H3PW12O40, significantly improving the catalytic efficiency of the heteropolyacid for the desired multi-component transformation. The yield of 3-substituted indoles strongly correlated with HPW loading (which spanned 3.2–51.6 wt %) and corresponding acid strength; the 51.6 wt % HPW/SBA-15 delivered 81% yield of 2-[(1H-indol-3-yl)(phenyl)methyl]malononitrile, approximately five times greater than that of the unsupported HPW, and exhibited a broad substrate scope for aromatic aldehydes

A magnetically-separable H3PW12O40@Fe3O4/EN-MIL-101 catalyst for the one-pot solventless synthesis of 2H-indazolo[2,1-b] phthalazine-triones

A magnetic inorganic-organic catalyst, PTA@Fe3O4/EN-MIL-101 (EN = ethylenediamine, PTA = phosphotungstic acid) was fabricated and characterized by XRD, HRTEM, FESEM, UV–vis, TGA-DTA, FT-IR, XPS and porosimetry. PTA retained the parent Keggin structure upon dispersion throughout the amine-functionalized chromium terephthalate metal-organic framework, over which magnetic Fe3O4 nanoparticles were previously introduced. The resulting composite heterogeneous solid acid was an active catalyst for the one-pot synthesis of diverse 2H-indazolo[2,1-b] phthalazine-triones in good → excellent yields under mild, solventless condition, and offers facile separation and excellent recyclability

H5PW10V2O40@VOx/SBA-15-NH2 catalyst for the solventless synthesis of 3-substituted indoles

Functionalization of mesoporous SBA-15 frameworks by transition metal oxides offers a flexible route to fabricate new heterogeneous catalysts. Here, an inorganic-organic hybrid nanoporous catalyst H5PW10V2O40@VOx/SBA-15-NH2, was prepared and utilized as an efficient, eco-friendly, and recyclable catalyst for the one-pot, multi-component synthesis of 3-substituted indoles by indole substitution with aldehydes and malononitrile under solvent-free conditions. Catalysts were prepared by the non-covalent attachment of H5PW10V2O40 to a 3 wt%VOx/SBA-15 nanoporous support through a 3-(triethoxysilyl)propylamine linker. VOx/SBA-15 was prepared by a one-pot hydrothermal synthesis from TEOS and vanadium(V) oxytri-tert-butoxide [VO(O-tBu)3]. The resulting H5PW10V2O40@VOx/SBA-15-NH2 material was characterized by bulk and surface analysis including N2 porosimetry, FE-SEM, XRD, XPS, FT-IR, TGA-DTA, UV–Vis and ICP-OES, evidencing retention of the heteropolyacid Keggin structure. H5PW10V2O40@VOx/SBA-15-NH2 exhibits high activity and excellent yields (70–95%) of 3-substituted indoles under mild conditions, with negligible deactivation

catena-Poly[[bis­(μ-3-amino­pyrazine-2-carboxyl­ato)-κ3 N 1,O:O;κ3 O:N 1,O)dilithium]-di-μ-aqua]

The title compound, [Li(C5H4N3O2)(H2O)]n, is composed of centrosymmetric dinuclear units, in which the LiI ions are bridged by two carboxyl­ate O atoms donated by two ligands. The dinuclear unit is nearly planar [r.m.s. deviation = 0.0125 (2) Å]. The LiI ion is coordinated by an N,O-chelating ligand, a bridging carboxyl­ate O atom from another ligand and two bridging water O atoms in a distorted trigonal-bipyra­midal geometry. The water O atoms bridge the dinuclear units into a polymeric mol­ecular column along [010]. The columns are held together by O—H⋯O and N—H⋯N hydrogen bonds. An intra­molecular N—H⋯O inter­action also occurs

A Highly Efficient and Green Catalytic Synthesis of 3,4-dihydro-pyrimidin-2-(1H)-ones (Thiones) Using 3-sulfonic Acid-1-imidazolopyridinium Hydrogen Sulfate under Solvent-free Conditions

The ionic liquid catalyst 3-sulfonic acid-1-imidazolopyridinium hydrogen sulfate, [Simp]HSO4 was found to be a highly active and green catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) under the solvent-free conditions. Avoiding organic solvents during the chemical reactions leading to an economic approach is effective. The reactions are characterized by high efficiency, short reaction time, high product yield, simple experimental procedure, availability of catalyst, and environmentally-friendly reaction conditions. This work is licensed under a Creative Commons Attribution 4.0 International License

H5PW10V2O40@VOx/SBA-15-NH2 catalyst for the solventless synthesis of 3-substituted indoles

Functionalization of mesoporous SBA-15 frameworks by transition metal oxides offers a flexible route to fabricate new heterogeneous catalysts. Here, an inorganic-organic hybrid nanoporous catalyst H5PW10V2O40@VOx/SBA-15-NH2, was prepared and utilized as an efficient, eco-friendly, and recyclable catalyst for the one-pot, multi-component synthesis of 3-substituted indoles by indole substitution with aldehydes and malononitrile under solvent-free conditions. Catalysts were prepared by the non-covalent attachment of H5PW10V2O40 to a 3 wt%VOx/SBA-15 nanoporous support through a 3-(triethoxysilyl)propylamine linker. VOx/SBA-15 was prepared by a one-pot hydrothermal synthesis from TEOS and vanadium(V) oxytri-tert-butoxide [VO(O-tBu)3]. The resulting H5PW10V2O40@VOx/SBA-15-NH2 material was characterized by bulk and surface analysis including N2 porosimetry, FE-SEM, XRD, XPS, FT-IR, TGA-DTA, UV–Vis and ICP-OES, evidencing retention of the heteropolyacid Keggin structure. H5PW10V2O40@VOx/SBA-15-NH2 exhibits high activity and excellent yields (70–95%) of 3-substituted indoles under mild conditions, with negligible deactivation