Shabnam Shaabani

Cellulose supported manganese dioxide nanosheet catalyzed aerobic oxidation of organic compounds

Cellulose supported manganese dioxide nanosheets, as a heterogeneous bio-supported and green catalyst, were synthesized by soaking porous cellulose in a potassium permanganate solution. The prepared catalyst was used effectively for the oxidation of various types of alkyl arenes, alcohols and sulfides to their corresponding carbonyl and sulfoxide compounds, respectively in high yields using air as the oxidant at ambient pressure. The catalyst can be recycled and reused in five runs without any significant loss of efficiency. The mild reaction conditions for the oxidation of alcohols and sulfides, high yields, recyclability of the catalyst, and very easy workup procedure are other advantages of this catalyst.

One-Pot Synthesis of Coumarin-3-carboxamides Containing a Triazole Ring via an Isocyanide-Based Six-Component Reaction

A facile, efficient, and environmentally friendly approach has been developed for the diversity oriented synthesis of trifunctional coumarin-amide-triazole containing compounds. A wide variety of pharmacologically significant and structurally interesting compounds were synthesized via a one-pot, six-component, tandem Knoevenagel/Ugi/click reaction sequence from readily available starting materials in ethanol at room temperature in excellent overall yields. Substituents could be independently varied at five different positions.

A novel one-pot pseudo-five-component condensation reaction towards bifunctional diazepine-tetrazole containing compounds: synthesis of 1H-tetrazolyl-1H-1,4-diazepine-2,3-dicarbonitriles and 1H-tetrazolyl-benzo[b][1,4]diazepines

A novel and efficient method has been developed for the one-pot synthesis of bifunctional diazepine-tetrazole containing compounds. 1H-Tetrazolyl-1H-1,4-diazepine-2, 3-dicarbonitrile and 1H-tetrazolyl-benzo[b][1,4]diazepine derivatives were synthesized in good yields using 2,3-diaminomaleonitrile or an aromatic diamine, ketones, trimethylsilyl azide, and an isocyanide in the presence of p-toluenesulfonic acid as a catalyst in methanol at room temperature.

Highly selective aerobic oxidation of alkyl arenes and alcohols: cobalt supported on natural hydroxyapatite nanocrystals

Cobalt was successfully immobilized on natural hydroxyapatite nanocrystals which were obtained from cow bones (Co–NHAp). The chemical, structural, and electronic properties of this nanobiocatalyst were investigated using flame atomic absorption spectroscopy (FAAS), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. Natural hydroxyapatite (NHAp) as the support enhanced both catalytic activity and selectivity in the liquid phase aerobic oxidation of alkyl arenes and alcohols to their corresponding carbonyl compounds. The use of air as an inexpensive oxidant, the recyclability of the Co–NHAp nanobiocatalyst without significant decrease in its catalytic activity and easy workup are some advantages of this work.

NaBrO3/guanidinium-based sulfonic acid: as a transition metal- and strong inorganic acid-free oxidation system for alcohols and alkyl arenes

The bromate anion as a safe, cheap, stable and easily stored oxidizing system has been utilized for the oxidation of a wide range of alcohols and alkyl arenes to the corresponding aldehydes and ketones. The reaction was performed in the presence of guanidinium-based sulfonic acid as a Bronsted acid organocatalyst in aqueous acetonitrile at room temperature. Products are isolated in high yields and the catalyst could be easily recovered and recycled.

Guanidinium-based sulfonic acid as a new Brønsted acid organocatalyst in organic synthesis in water

Guanidinium-based sulfonic acid as a new Brønsted acid organocatalyst has been synthesized, characterized, and applied for the synthesis of 3,4-dihydroquinoxalin-2-amine, 1,6-dihydropyrazine-2,3-dicarbonitrile, triazolo[1,2-a]indazole-trione, and spiro triazolo[1,2-a]indazole-tetraone derivatives in an aqueous medium. The catalytic system, reported here, possesses the advantages of both homogeneous and heterogeneous catalysts and can be repetitively used in water.Graphical Abstract

A passerini-type condensation: a carboxylic acid-free approach for the synthesis of the α-acyloxycarboxamides.

A Passerini-type condensation for the synthesis of α-acyloxycarboxamides starting from simple and readily available inputs, including an isocyanide, aldehydes and water in the presence of trimethylsilyl azide as a catalyst under reflux conditions in toluene in good yields, is described.

Natural hydroxyapatite supported cobalt tetrasulfophthalocyanine: a green, renewable and biomaterial-based heterogeneous catalyst for selective aerobic oxidation of alkyl arenes and alcohols

Natural hydroxyapatite supported cobalt tetrasulfophthalocyanine (CoTSPc-NHAp) as a green, renewable and biomaterial-based heterogeneous catalyst that mediates oxidation of various secondary benzylic C–H bonds, secondary benzylic and primary and secondary aliphatic alcohols to their corresponding aldehydes and ketones in high yields and selectivity without any additional oxidizing reagent is reported. The structure of the synthesized catalyst was characterized by inductively coupled plasma-optical emission spectrometry (ICP-OES), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and the energy dispersive spectroscopy (EDS) analysis.

Guanidinium-based sulfonic acid: an efficient Brønsted acid organocatalyst for the synthesis of fused polycyclic dihydropyridines in water

An efficient and eco-friendly protocol for the synthesis of polycyclic dihydropyridine scaffolds has been developed from readily accessible 4-hydroxycoumarin, aldehydes, and ammonium acetate in the presence of guanidinium-based sulfonic acid as a Brønsted acid organocatalyst. This method provides several advantages, such as simple work-up procedure, environmentally benign, recyclable catalyst, and high yields. In addition, water was chosen as a green solvent.Graphical Abstract

Synthesis of furan-fused quinoxaline tetracyclic scaffolds via a three-component isocyanide-based reaction

A novel isocyanide-based three-component catalyst-free approach for synthesis of furan-fused quinoxaline tetracyclic frameworks in good yields via reaction of 6-hydroxybenzo[f]quinoxaline-2,3-dicarbonitrile, an aromatic aldehyde, and an isocyanide under reflux conditions in toluene is described.Graphical Abstract