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Reaction of aldehydes and ketones with ferrocene, in the presence of trifluoroacetic acid, afforded a series of stable long lived alpha-ferrocenylalkyl carbocations which were characterized by 13C-NMR spectroscopy. When this reaction was attempted using tetraphenylcyclopentadienone, quite unexpectedly the corresponding dihydro derivative 3 was isolated, in very good yield. Formation of this compound may require ferrocene acting as a reducing agent.

It is difficult to overestimate the importance of nucleoside triphosphates in cellular chemistry: They are the building blocks for DNA and RNA and important sources of energy. Modifications of biologically important organic molecules with fluorine are of great interest to chemists and biologists because the size and electronegativity of the fluorine atom can be used to make defined structural alterations to biologically important molecules. Although the concept of nonhydrolyzable nucleotides has been around for some time, the progress in the area of modified triphosphates was limited by the lack of synthetic methods allowing to access [bisCF.sub.2]-substituted nucleotide analogs--one of the most interesting classes of nonhydrolyzable nucleotides. These compounds have 'correct' polarity and the smallest possible steric perturbation compared to natural nucleotides. No other known nucleotides have these advantages, making [bisCF.sub.2]-substituted analogs unique. Herein, we report a concise route for the preparation of hitherto unknown highly acidic and polybasic bis(difluoromethylene)triphosphoric acid 1 using a phosphorous(III)/phosphorous(V) interconversion approach. The analog 1 compared to triphosphoric acid is enzymatically nonhydrolyzable due to substitution of two bridging oxygen atoms with [CF.sub.2] groups, maintaining minimal perturbations in steric bulkiness and overall polarity of the triphosphate polyanion. The fluorinated triphosphoric acid 1 was used for the preparation of the corresponding fluorinated deoxynucleotides (dNTPs). One of these dNTP analogs (dT) was demonstrated to fit into DNA polymerase beta (DNA pol [beta]) binding pocket by obtaining a 2.5 [Angstrom] resolution crystal structure of a ternary complex with the enzyme. Unexpected dominating effect of triphosphate/[Mg.sup.2+] interaction over Watson--Crick hydrogen bonding was found and discussed. DNA polymerase beta | nonhydrolyzable nucleotides | fluorinated triphosphate | pentabasic acid | isopolarity and bioisotericity doi/ 10.1073/pnas.1007430107

High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/ cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of superelectrophilic diprotonated, and dimethylated molecular chlorine ([Cl.sub.2]) and bromine ([Br.sub.2]) dications. Diprotonated chlorine and diprotonated bromine dications 3a and 6a, respectively, were found to be lowest energy minima. The isomeric dications, 3b and 6b, are also minima on the potential energy surfaces but they are significantly less stable than the structures 3a and 6a by 33.6 and 30.9 kcal/mol, respectively. On the basis of computed G2 energies, proton affinities and related thermodynamic parameters were also calculated. Dications 3a and 6a have substantial kinetic barriers for deprotonation. Their homolytic dissociation are however facile. Dimethylated molecular chlorine and bromine dications 3g and 6g, respectively, were also found to be global energy minima. These vicinal dihalonium or the corresponding protosolvated species are expected to form either in the superacidic media or in the gas phase. ab initio | halonium | superacid | gas phase doi/ 10.1073/pnas.1001603107

Highly efficient stereoselective 1,4-addition of racemic [alpha]-fluoro-[alpha]-nitro(phenylsulfonyl)methane (FNSM) as a fluoromethyl pronucleophile to [alpha],[beta]-unsaturated ketones using a wide range of chiral organobifunctional catalysts under moderate conditions in the absence of an additional base has been achieved. A series of catalysts was screened for the enantioselective addition of FNSM to chalcones and the catalysts CN I, CD I, QN I-IV, and QD I were found to enable this reaction, successfully providing exclusive 1,4-addition products stereoselectively in high yields (conversion, diastereomeric ratio, and enantiomeric excess). Studies involving a model reaction and systematic analysis of the absolute configuration support the suggested mechanism. fluorinated substituents | H bonding | stereoselective catalysis | steric effect

High level ab initio calculations are used to obtain the structural information on primary, secondary and tertiary cyclobutylmethyl cations. The GIAO-CCSD(T) derived [super 13]C NMR chemical shifts of the selected carbocations are calculated to detect the nature and extent of charge delocalization into the cyclobutyl ring.

The synthesis of [alpha]-aminonitriles and their fluorinated analogs has been carried out in high yield and purity by the Strecker reaction from the corresponding ketones and amines with trimethylsilyl cyanide using gallium triflate in dichloromethane. Monofluoro-, difluro-, or trifluoromethyl groups can be incorporated into the [alpha]-aminonitrile product by varying the nature of the fluorinated ketones. Study with various fluorinated and nonfluorinated ketones reveals that the choice of proper catalyst and the solvent system (suitable metal triflates as a catalyst and dichloromethane as a solvent) plays the key role in the direct Strecker reactions of ketones. three-component reaction | [alpha]-aminonitriles

Cyanosilylation of aldehydes and aliphatic ketones can be carried out in dimethylformamide even without the use of any catalyst. In the presence of nucleophilic catalysts such as carbonate and phosphate salts, the reaction rate is significantly enhanced. nature of solvent

Ab initio/GIAO-CCSD(T) method is used to study the [.sup.13.C] NMR chemical shifts of bicyclic and related strained olefins. The results show that the relative energies of the various conformers of ethylene correlate very well with the [.sup.13.C] NMR chemical shifts, reflecting the linear dependence of the [.sup.13.C] NMR chemical shifts with the internal strain of the molecules.

The preparation and properties of 1:2 complex of BF3 and 2,2,2-trifuloroethanol and its successful use as a strong acid catalyst in different organic transformations is described. Results reveal that a 1:2 complex, BF3.2CF3-CH2OH (BF3.2TFE) formed from BF3 and CF3Ch2OH could act as an efficient superacidic catalyst for many organic synthetic transformations.

Some new aspects of electrophillic hydrocarbon chemistry that were developed in collaboration with George A. Olah and other investigators are discussed. The development was conducted to characterize such intermediates under so-called long-lived stable ion conditions that lead to the understanding of their structures and reactivity patterns and resulted in a paradigm shift in comphending the stability and reactivity of electrophilic intermediates in superacid media.

The mechanism of the oxygenation of alkane C-H bonds with methyl(trifluoramethyl)dioxirane is studied through the effect of the substituent and solvent on the rate of oxygenation of 2-substituted adamantanes. The results suggest a remarkable electron deficiency at the reacting carbon atom in the transition state leading to the regular oxygenation products.

Electrophilic triethylsilylation of diphenylketene leads to exclusive C-silylation giving the diphenyl(triethylsilyl)acetyl cation in the solution phase even though density functional theory calculations at the B3LYP/6-311+G* level indicate that the O-silylation of diphenylketene is preferred over C-silylation by 5.4 kcal/mol in the gas phase. On the other hand, in the case of the parent ketene, similar density functional theory calculations show that C-silylation is preferred over O-silylation by 8.2 kcal/mol.

An efficient new electrophilic reagent combination of N-Halosuccinimides (NXS)/BF3-H2O is developed as BF3-H2O is more economic, easy to prepare, nonoxidizing and offers high acidity. The structural aspects of the BF3-H2O complex are investigated.