Planar Chromatography of Some 1-Arylpiperazines Behaving as Dopaminergic Ligands

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica...     

Microwave-assisted synthesis of allylic amines: considerable rate acceleration in the hydrozirconation-transmetalation-aldimine addition sequence

The hydrozirconation of alkynes with zirconocene hydrochloride and the dimethylzinc-mediated addition of alkenylzirconocenes to diphenylphosphinoyl imines can be greatly accelerated with microwave irradiation, resulting in a convenient and rapid one-pot process for the preparation of synthetically useful allylic amines.     

A simple,convenient and expeditious approach to cineol

A convenient two‐step protocol preparation of cineol (1‐isopropyl‐4‐methyl‐7‐oxabicyclo[2,2,1]heptane) from α‐terpineol (p‐menth‐1‐en‐8‐ol) is reported. The phenylselenoetherification of α‐terpineol with PhSeX (X = Cl, Br, I) as a key step is described. α‐Terpineol reacts with PhSeX to form the corresponding phenylselenoether in short reaction time and in quantitative yield. A subsequent reduction with Bu₃SnH to cineol proceeds in high yield (98%) © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:468–470, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20044     

Metal-catalyzed di-tert-butylsilylene transfer: synthesis and reactivity of silacyclopropanes

Metal-catalyzed di-tert-butylsilylene transfer was developed as a mild, operationally simple, functional-group-tolerant method for silacyclopropane formation. Di-tert-butylsilylene was transferred from cyclohexene silacyclopropane 1 to an alkene through the use of a metal salt. Silacyclopropanation occurred at temperatures as low as -27 degrees C when AgOTf or AgOC(O)CF(3) were used as catalysts. Complex silacyclopropanes were formed stereospecifically and diastereoselectively from functionalized alkenes. Silacyclopropanes reacted with various carbonyl compounds, including aldehydes, ketones, formate esters, and formamides, in an overall process that efficiently converts alkenes into oxasilacyclopentanes with defined stereochemistry.     

Reversible gas-phase redox processes catalyzed by Co-exchanged MFU-4l(arge)

Postsynthetic metal ion exchange in a benzotriazolate-based MFU-4l(arge) framework leads to a Co(II)-containing framework with open metal sites showing reversible gas-phase oxidation properties.     

Parallel Interactions at Large Horizontal Displacement in Pyridine–Pyridine and Benzene–Pyridine Dimers

A study of crystal structures from the Cambridge Structural Database (CSD) and DFT calculations reveals that parallel pyridine–pyridine and benzene–pyridine interactions at large horizontal displacements (offsets) can be important, similar to parallel benzene–benzene interactions. In the crystal structures from the CSD preferred parallel pyridine–pyridine interactions were observed at a large horizontal displacement (4.0–6.0 Å) and not at an offset of 1.5 Å with the lowest calculated energy. The calculated interaction energies for pyridine–pyridine and benzene–pyridine dimers at a large offset (4.5 Å) are about 2.2 and 2.1 kcal mol^?1, respectively. Substantial attraction at large offset values is a consequence of the balance between repulsion and dispersion. That is, dispersion at large offsets is reduced, however, repulsion is also reduced at large offsets, resulting in attractive interactions.     

Selective pervaporation of water through a nonselective microporous titania membrane by a dynamically induced molecular sieving mechanism

Pervaporation experiments were performed on microporous titania membranes using several binary liquids containing 2-20 wt % water. The membrane was nonselective in the separation of water from alcohols and p-dioxane but showed a remarkably high selectivity in the separation of water from ethylene glycol/water mixtures with < or =15 mol % water. The absence of selectivity under most conditions is explained by the large pore size (0.9 nm) of microporous titania. The high selectivity for water in the separation from ethylene glycol can be explained by the formation of a hydrogen-bonded network of ethylene glycol in the micropores, which blocks transport of ethylene glycol, while water can still permeate through. These networks are disrupted by water at higher concentrations, leading to full loss of membrane selectivity.     

New tin templates for the synthesis of macrocyclic polythiaether-polythiaester ligands

The preparation of new tin templates, stannathianes 1-3 is described. New templates have been successfully applied to the synthesis of macrocyclic polythialactones 4-9 by cyclization of corresponding stannathianes 1-3 with pimeloyl dichloride.     

Optical study of the formation of pyrrolo[2,3-d]pyrimidine-based fluorescent nanoaggregates

Pyrrolo[2,3-d]pyrimidine derivatives possessing different sterically-hindered end-groups at position 7 of the heterocycle were studied and compared with respect to nanoaggregate formation ability by the reprecipitation method in aqueous solutions. The emergence of nanoaggregates with an increasing water fraction in THF/water mixture was traced by observing sudden changes in spectral and transient fluorescence dynamics accompanied by fluorescence efficiency turn-on. The aggregation induced emission with a maximal 20-fold emission efficiency enhancement was obtained. Tuning of the nanoaggregates sizes from about 50 nm to 600 nm by increasing the THF/water ratio was revealed by electron microscopy. Almost perfect spherical shapes of the nanoaggregates and their structureless fluorescence bands similar to those of their neat amorphous films suggested an amorphous-like nature of the pyrrolo[2,3-d]pyrimidine-based nanoparticles.     

Microwave-assisted "libraries from libraries" approach toward the synthesis of allyl- and C-cyclopropylalkylamides

Cascade reactions of internal and terminal alkynes, zirconocene hydrochloride, dimethylzinc, and phosphinoyl imines (prepared in one step from aldehydes and diphenylphosphinoyl amide) lead to allylic phosphinoyl amides after aqueous workup. Microwave acceleration allows the completion of this one-pot reaction sequence in 10 min. These allylic amides can be converted into a variety of derivatives, including carbamates and sulfonamides, or reacted prior to workup with diiodomethane to give novel C-cyclopropylalkylamides. A solution-phase "libraries from libraries" approach was used to generate an intermediate 20-member library which was subsequently expanded to a 100-member library by a series of N-functionalizations. The biological activity was evaluated in an assay for competitive binding to the estrogen receptor (ERalpha), revealing three potent lead compounds of a new structural type.