Aza-Henry reaction with perfluoroalkylated cyclic ketimines

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Microwave-assisted synthesis of ultra-small iron oxide nanoparticles for biomedicine

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Unusual N,Se-heterocycles with cyclic Se–N+ bond of isoselenazolopurinium type

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Synthesis of cyclic norspermidine derivative of protohemin IX

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1,1,1-Trifluoropropan-2-ammonium triflate enantiomers: stereoselective synthesis and direct use in reaction with epoxides

A three-step synthesis of enantiomerically enriched 1,1,1-trifluoro-2-propanamine based on the use of a chiral sulfinamide auxiliary is described. The reduction of the geometrically pure Z-sulfinimine (NOE, HOE) with NaBH₄ or l-Selectride leads to the corresponding (R)- or (S)-configured amine derivatives (X-ray crystallographic analysis) with 92–96% de. The typical models to explain the stereoselection for these reducing agents fail to rationalize the obtained stereoselectivities, and an in situ imine isomerization is proposed to occur. The direct use of the hydrochloric acid salt (with excess Et₃N) of this poorly nucleophilic amine for epoxide opening reactions is not possible due to the higher nucleophilicity of chloride. Hence, a novel triflate salt is introduced, synthesized through ready sulfinamide hydrolysis with trimethylsilyl triflate, which can be used directly, without the need of isolating the pure amine beforehand.     

A novel direct catalytic production of p-xylene from isobutanol

A new one-step production of p-xylene (along with other liquid hydrocarbons) from isobutanol is catalyzed by zinc and chromium promoted micro-mesoporous MFI/MCM-41 composite (synthesized by hydrothermal-microwave method). The use of isobutanol of biogenic origin is in accordance with the principles of ‘green chemistry’.

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Dendro-shaped blocks with arylsulfanyl fragments based on p-toluic acid

Chloromethylation of p-toluic acid affords 3,5-bis(chloro- methyl)-4-methylbenzoic acid whose subsequent treatment with arenethiols brings about spacer dendrimeric blocks containing polyfluoroarylsulfanyl fragments in a total yield of 60-75%.     

Triacetic acid lactone as a bioprivileged molecule in organic synthesis

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Enantiomerically pure piperazines via NaBH4/I2 reduction of cyclic amides

Enantiomerically pure (3S,7R,8aS)-3-phenyloctahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-methyl octahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-isopropyloctahydropyrrolo[1,2-a]pyrazine-7-ol and (3S,7R,8aS)-3-isobutyloctahydropyrrolo[1,2-a]pyrazine-7-ol 16d were synthesized via preparation of the corresponding cyclic amides from enantiomerically pure l-proline and hydroxyproline derivatives followed by reduction using sodium borohydride-iodine.     

Chemical modification of nanocrystalline cellulose for improved interfacial compatibility with poly(lactic acid)

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A planar chiral six-membered cyclic (amino)(ferrocenyl)carbene and its sulfur adduct

A planar chiral ferrocene-fused cyclic aldimine was synthesized and a series of iminium salts were divergently prepared from it. The new carbene was generated from a salt by simple deprotonation with a strong base and identified by a carbene trapping experiment with sulfur. The sulfur adduct was fully characterized and its crystal structure implied that the new carbene would create an excellent chiral environment when used as a catalyst or a ligand in catalytic asymmetric synthesis.     

Insights into a surprising reaction: the microwave-assisted direct esterification of phosphinic acids

It is well-known that phosphinic acids do not undergo direct esterifications with alcohols under thermal conditions. However, the esterifications take place under microwave (MW) irradiation due to the beneficial effect of MW. As a comparison, maximum 12-15% conversions were observed on traditional heating. It was proved experimentally that the MW-assisted esterifications are not reversible under the conditions applied that may be the consequence of the hydrophobic medium established by the long chain alcohol/phosphinic ester. Neither the thermodynamic, nor the kinetic data obtained by high level quantum chemical calculations justify the direct esterification of phosphinic acids under thermal conditions. The thermodynamic data show that there is no driving force for the reactions under discussion. As a consequence of the relatively high values of activation enthalpy (102-161 kJ mol(-1)), these esterifications are controlled kinetically. Comparing the energetics of the esterification of phosphinic acids and the preparative results obtained under MW conditions, one can see the potential of the MW technique in the synthesis of phosphinates. During our study, a series of new cyclic phosphinates with lipophilic alkyl groups was synthesized.     

Microwave-assisted synthesis of magnetite nanoparticles possessing superior magnetic properties

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Synthesis of 1-(hydroxyaryl)furo[3,4-c]pyridines from 1-amino(alkoxy)furo[3,4-c]pyridines and (poly)phenols

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3-Menthoxybiphenyl-4-carboxylic acid: a versatile resolving agent and reagent for determination of the absolute configuration of benzylic alcohols

A versatile reagent for the chiral resolution and determination of the absolute configuration of benzylic alcohols, (?)-3-menthoxybiphenyl-4-carboxylic acid, is reported. (?)-3-menthoxybiphenyl-4-carboxylic acid was condensed with racemic benzylic alcohols to yield diastereomeric 3-menthoxybiphenyl-4-carboxylic esters, which were separated by reversed-phase HPLC. The absolute configurations of the 3-menthoxybiphenyl-4-carboxylic esters were unambiguously determined by exciton-coupled circular dichroism. Hydrolysis of the 3-menthoxybiphenyl-4-carboxylic esters yielded enantiopure alcohols, and their absolute configurations were simultaneously determined.     

Hybrid membranes based on short side chain perfluorinated sulfonic acid membranes (Inion) and heteropoly acid salts

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Template synthesis of methylammonium lead iodide in the matrix of anodic titanium dioxide via the direct conversion of electrodeposited elemental lead

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Diastereoselective vinylogous Mannich reaction of perfluoroalkylated cyclic imines with 2-trimethylsilyloxyfuran

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Self-condensation of 2-(ethoxalylmethyl)chromones into new derivatives of isotetronic acid

2-(Ethoxalylmethyl)chromones undergo dimerization to dichromonyl derivatives of isotetronic acid in 62–89% yields on refluxing with 2,3-diaminopyridine in ethanol for 1–2 h.