Nafion-H?: A recyclable and diastereoselective solid acid catalyst for three-component mannich reaction

One-pot, three-component Mannich reactions of ketones, aldehydes and amines are efficiently catalyzed by heterogeneous Nafion-H? ambient temperature to give the corresponding ??-amino ketones compounds in good to excellent yields. The catalyst can be easily recovered and reused without any decrease of activity for at least four times. Diastereoselective products can be obtained in Mannich reaction of aliphatic ketone.     

Carbon-based solid acid: an efficient and reusable catalyst for the diastereoselective ring opening reaction of α-epoxyketones

Carbon-based solid acid efficiently catalyzes diastereoselective ring opening of α-epoxyketones in the presence of methanol to produce the corresponding α-hydroxy-β-methoxyketones in excellent yield.     

A rapid and highly efficient Michael addition of methoxybenzenes and indoles to α,β-unsaturated ketones using BF3·OEt2 as a catalyst

An efficient and general protocol is described for the Michael addition of α,β-unsaturated ketones with electron-rich arenes/indoles to give alkylated arenes/indoles under mild reaction condition at room temperature. Shorter reaction time, convenient and good isolated yields are the significant features of this protocol. Moreover, the procedure is environmentally benign in nature and applicable to variety of arenes/indoles as well as α,β-unsaturated ketones.     

Polyvinylpolypyrrolidone-supported triflic acid (PVPP·OTf) as a new,efficient, and recyclable heterogeneous catalyst for the synthesis of bis-indolyl methane derivatives

A simple, inexpensive, environmentally friendly and efficient route for the synthesis of bis-indolyl methane derivatives by the reaction of indole or N-methyl indole with aldehydes using polyvinylpolypyrrolidone-supported triflic acid (PVPP·OTf) as a catalyst is described. PVPP·OTf catalyst is air-stable, heterogeneous, cost-effective, easy to handle, and easily removed from the reaction mixtures.     

Ash of pomegranate peels (APP): A bio-waste heterogeneous catalyst for sustainable synthesis of α,α′-bis(substituted benzylidine)cycloalkanones and 2-arylidene-1-tetralones

Research on Chemical Intermediates - α,α′-bis(substituted benzylidene)cycloalkanones were efficiently prepared from variously substituted aldehydes and cycloalkanones in water by...     

Silica supported perchloric acid （HClO4-SiO2）： A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of amidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.     

MgCl(2)·4((CH(3))(2)CHCH(2)OH): A new molecular adduct for the preparation of TiCl(x)/MgCl(2) catalyst for olefin polymerization

A new molecular adduct of MgCl(2) with isobutanol, namely MgCl(2)·4((CH(3))(2)CHCH(2)OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O(6) breathing mode and the formation of the adduct. The diffraction feature at 2θ = 7.8° (d = 11.223 ?) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl(2)·isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.     

Enantioselective organocatalytic Michael addition of 2-arylacetates and 2-arylacetonitriles having an electron-withdrawing group to α,β-unsaturated aldehydes

The asymmetric organocatalytic Michael addition reaction of 2-arylacetates and 2-arylacetonitriles having an electron-withdrawing group to α,β-unsaturated aldehydes has been established using diphenylprolinol trimethylsilyl (TMS) ether as organocatalyst. The 2-arylacetates and 2-arylacetonitriles having NO₂-, CO₂Me-, and CN-functional groups on the aromatic ring can be used in this reaction. The desired products were obtained with good to excellent yields and high enantioselectivities (up to 97% ee).     

Synthesis of 3-deoxy-d-manno-2-octulosonic acid (Kdo) and d-glycero-d-talo-2-octulosonic acid (Ko) and their α-glycosides

Reaction of 2,3:5,6-di-O-isopropylidene-d-mannofuranose 1 with C-2 lithio derivatives of glyoxylate mercaptal in the presence of MgBr₂ afforded d-glycero-d-galacto-2-octulosonates 2 and 3, respectively. Their 3-O-deoxygenation led to Kdo. N-Iodosuccinimide treatment of 3 gave thioglycoside 11 directly, which was transformed into Ko derivative 12 via epimerisation of the 3-hydroxy group. 3-O-Benzoylation of 12 and then transformation into phosphite furnished 15, an efficient glycosyl donor. Reaction of 15 with 6-O-unprotected glucosamine derivative 22 as acceptor gave α-glycoside 23, which was successfully transformed either into Kdo-disaccharide 27 or into Ko-disaccharide 29.     

(NMCp)2TiCl2-catalyzed reduction of aliphatic,aromatic and α,β-unsaturated ketones by grignard reagent

Aliphatic, aromatic and α,β-unsaturated ketones were readily reduced to the corresponding secondary alcohols by iso-propylmagnesium bromide in the presence of a catalytic amount of bis(neomenthylcyclopentadienyl)titanium dichloride. A possible mechanism is discussed.     

A solventless protocol for the Michael addition of aromatic amides to α,β-unsaturated esters promoted by microwave irradiation

A very simple and efficient solvent-free method for the preparation of N-benzoylated β-amino esters (protected β-amino acids) via the microwave-assisted Michael addition of aromatic amides to α,β-unsaturated esters in the presence of Cs₂CO₃ and tetrabutylammonium bromide (TBAB) is described. The advantages of this method are efficiency, high yields and short reaction times.     

A sulfonic acid functionalized ionic liquid as a homogeneous and recyclable catalyst for the one-pot synthesis of α-aminophosphonates

A sulfonic acid functionalized ionic liquid is used as a Brønsted acid catalyst for the one-pot, three-component synthesis of α-aminophosphonates from aldehydes and ketones at room temperature in water. This homogeneous catalytic procedure is simple and efficient and the catalyst can be reused at least six times without any noticeable decrease in catalytic activity.     

Versatile methodology for the synthesis and α-functionalization of (2R,3aS,7aS)-octahydroindole-2-carboxylic acid

An improved strategy for the effective synthesis of enantiomerically pure (2R,3aS,7aS)-octahydroindole-2-carboxylic acid (Oic), based on the formation of a trichloromethyloxazolidinone derivative, has been developed. Additionally, the completely diastereoselective α-alkylation of such oxazolidinone provides a very convenient and concise route to enantiopure α-tetrasubstituted derivatives of this Oic stereoisomer.     

Enantioselective syntheses of (−)-pinellic acid, α- and β-dimorphecolic acid

An efficient enantioselective convergent approach for the synthesis of (−)-pinellic acid 1, α- and β-dimorphecolic acid (2 and 3) from 1,9-nonane diol is described. The synthetic strategy features Sharpless asymmetric hydroxylation, Sonogashira coupling and Birch reduction.     

Sulfonated poly(4-vinylpyridine) heteropolyacid salts:A reusable green solid catalyst for Mannich reaction

Sulfonated poly（4-vinylpyridine） heteropolyacid salts acted as a heterogeneous catalyst to effectively catalyze the one-pot synthesis of β-amino carbonyl compounds via the Mannich reaction between aromatic aldehydes, aromatic ketone, and aromatic amines. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity.     

Ni2+ supported on hydroxyapatite-core-shell γ-Fe2O3 nanoparticles: a novel,highly efficient and reusable lewis acid catalyst for the regioselective azidolysis of epoxides in water

In this research, Ni²⁺ supported on hydroxyapatite-core-shell magnetic γ-Fe₂O₃ nanoparticles (γ-Fe₂O₃@HAp-Ni²⁺) as a novel, efficient, reusable and heterogeneous catalyst was reported. In this protocol, we used this catalyst for the ring opening of epoxide with sodium azide in water. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.     

Crystal structure of α-(N-benzoxazoline-2-one) acetic acid hydrate,solvate, and salts

The crystal structure of α-(N-benzoxazoline-2-one) acetic acid is studied in the following forms: hydrate, solvate with formic acid, organic monoethanolammonium salt (NН₂(CH₂)₂OH) in two polymorphs produced by minor changes in the crystallization temperature, and also its ethylenediammonium salt (NН₂(CH₂)₂NH₂) in the 2:1 ratio, where amino groups participate in the deprotonation of two molecules of α-(N-benzoxazoline-2-one) acetic acid. Weak intermolecular hydrogen and dative bonds in the crystals consisting of different molecules are analyzed.     

Catalytic asymmetric Michael addition of α,β-unsaturated aldehydes to Ni(II) complexes of the Schiff base of glycine

The conjugate addition of Ni(II) complexes of glycine Schiff base to α,β-unsaturated aldehydes catalyzed by (S)-2-(diphenyl(trimethylsilyloxy)methyl)pyrrolidine afforded adducts in excellent yields with up to 49:1 dr and 95% ee. This method enables the construction of two adjacent chiral centers in one step, and offers an alternative route to chiral α-amino acid derivatives.