Gallium (III) triflate catalyzed efficient Strecker reaction of ketones and their fluorinated analogs.

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.

Structural studies of nonclassical cyclobutylmethyl cations by the ab initio method.

Ab initio calculations at the MP2/cc-pVTZ level show that the cyclobutylmethyl cation is a nonclassical sigma-delocalized species, which is distinct from the global minimum C2-symmetric cyclopentyl cation (Schleyer, P. v. R.

Meiotic spindle and zona pellucida characteristics as predictors of embryonic development: a preliminary study using PolScope imaging.

This study assesses meiotic spindle and zona pellucida characteristics using the PolScope, and analyses their relationship to embryonic development potential. A total of 205 matured oocytes retrieved from 25 patients undergoing ovarian stimulation were imaged for meiotic spindle and zona pellucida characteristics using the PolScope. After intracytoplasmic sperm injection, the oocytes were cultured and assessed for progression to blastocysts.

Efficient one-pot synthesis of fluorinated benzimidazolines, benzothiazolines, benzoxazolines, and dihydrobenzoxazinones using gallium(III) triflate as a catalyst.

One-pot synthesis of fluorinated benzimidazolines, benzothiazolines, benzoxazolines, and dihydrobenzoxazinones was easily achieved under mild conditions in high yields and purity through gallium(III) triflate mediated condensation-cyclization. Introduction of fluorine atoms favors the formation of the five-membered heterocycles over seven-membered heterocycles. [reaction: see text].

Comparative study of the hypercoordinate ions C7H9+ and C8H9+ by the ab initio/GIAO-CCSD(T) method.

A comparative study of the hypercoordinate square-pyramidal carbocations C7H9+ and C8H9+ was performed by the ab initio/GIAO-CCSD(T) method. The structures and 13C NMR chemical shifts of the cations were calculated at the GIAO-CCSD(T)/tzp/dz//MP2/cc-pVTZ level. The bishomo square pyramidal structure 1 was calculated for C7H9+ at the MP2/cc-pVTZ level.

Facile synthesis of TMS-protected trifluoromethylated alcohols using trifluoromethyltrimethylsilane (TMSCF3) and various nucleophilic catalysts in DMF.

Organofluorine compounds are becoming increasingly important in different fields, such as material science, agro chemistry, and the pharmaceutical industry. Nucleophilic trifluoromethylation is one of the widely used methods to incorporate a trifluoromethyl moiety into organic molecules. We have carried out extensive studies to develop varieties of easily accessible nucleophilic catalysts to promote such reactions.

Cerebral salt wasting syndrome in a patient with tuberculous meningitis.

We report a case of a 65 year male with meningitis who had polyuria, severe hyponatremia, volume depletion and very high urinary sodium excretion. He was diagnosed to have cerebral salt wasting syndrome based on clinical and laboratory parameters.

Preparation of tri- and difluoromethylated amines from aldimines using (trifluoromethyl)trimethylsilane.

[reaction: see text] Addition of a trifluoromethyl group into aldimines was accomplished using (trifluoromethyl)trimethylsilane with tetraalkylammonium fluorides as initiators, and the resulting adducts were converted to difluoromethylated imines in the presence of excess fluoride. The imines were reduced to difluoromethylated amines using sodium borohydride.

Chiral alpha-branched benzylic carbocations: diastereoselective intermolecular reactions with arene nucleophiles and NMR spectroscopic studies.

The chiral benzylic alcohols 1-6 were prepared and subjected to S(N)1-type displacement reactions with various arene nucleophiles in acidic medium. Under optimized conditions (HBF(4).OEt(2), CH(2)Cl(2), -78 degrees C --> r.

Comparative ab initio study of the structures and stabilities of the ethane dication C2H6(2+) and its silicon analogues Si2H6(2+) and CSiH6(2+).

Ab initio MP2/6-311G and QCISD(T)/6-311G levels as well as Gaussian-2 theory were used to perform a comparative study of the structures and stabilities of the ethane dication C(2)H(6)(2+) and its silicon analogues Si(2)H(6)(2+) and CSiH(6)(2+). Similar to previous HF/6-31G results, our present calculations also indicate that the two-electron three-center (2e-3c) bonded carbonium-carbenium structure 1 is more stable than the doubly hydrogen bridged diborane-type structure 2 by about 12 kcal/mol. For the silicon analogue Si(2)H(6)(2+) the calculations, however, indicate that the 2e-3c bonded siliconium-silicenium structure 8 is about 9 kcal/mol less stable than doubly hydrogen bridged structure 9.

Ab Initio/GIAO-CCSD(T) study of bicyclic and related strained olefins. Structures and 13C NMR chemical shifts.

Bicyclic and related strained olefins were studied by the ab initio/GIAO-CCSD(T) method. Structures and (13)C NMR chemical shifts of the olefins were calculated using ab initio/GIAO-CCSD(T) method. The delta(13)C of the olefinic carbons of the yet unknown bicyclo[1.

Assessment of uterine cavity by hysteroscopy in assisted reproduction programme and its influence on pregnancy outcome.

Objective: The aim of the study was to evaluate if the diagnosis and treatment of uterine cavity abnormalities by hysteroscopy in patients undergoing IVF programme is of any value in improving clinical pregnancy outcome.

Methods: 520 patients participated in this prospective randomized study and were classified into two groups. Group I (n = 265) without office hysteroscopy.

BF3.2CF3CH2OH (BF3.2TFE), an efficient superacidic catalyst for some organic synthetic transformations.

BF3.2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid.

Electrophilic intermediates and their reactions in superacids.

Acid-catalyzed reactions have played a major role in hydrocarbon chemistry involving electron-deficient intermediates such as carbocations, carbodications, onium ions, etc. The pioneering discovery of the use of superacids by George A. Olah, in the early 1960s, to characterize such intermediates under so-called long-lived stable ion conditions led to the understanding of their structures and reactivity patterns much more clearly.

Successful pregnancy with laparoscopic oocyte retrieval and in-vitro fertilisation in mullerian agenesis.

A 28-year-old woman with mullerian agenesis presented with primary infertility and was considered for laparoscopic oocyte retrieval and in-vitro fertilisation. Her 27-year-old younger sister served as a gestational carrier. The patient underwent ovarian stimulation and 11 mature oocytes were retrieved by laparoscopy.

Theoretical study of AlH(2+)n (n=1-7) dications.

The structures and stability of AlH(2+)n (n = 1-7 )dications were calculated at the ab initio MP2/aug-cc-pVTZ level of theory. The dications AlH(2+) 1 and AIH(2+2) 2 were characterized to be unstable thermodynamically. However, these and the stable dications, AlH(2+)n (n = 3-7) 3-7 have considerable kinetic barriers for deprotonation.

Vogt-Koyanagi-Harada syndrome with intracranial meningioma: an as yet unreported association.

Case Report: We document a previously unreported association of Vogt-Koyanagi-Harada (VKH) syndrome with intracranial meningioma. A female patient with diminished vision, exudative retinal detachment, and headache was diagnosed with VKH syndrome, more precisely a Harada form of disease with intracranial meningioma, on the basis of exudative retinal detachment, typical fundus fluorescein findings, and magnetic resonance imaging. With intravenous steroid therapy, visual acuity improved and the detachment settled within a week.

Ab initio/GIAO-CCSD(T) study of propenoyl (H2C=CH-CO+) and isopentenoyl ((CH3)2C=CH-CO+) cations and their superelectrophilic protonated dications.

Structures of superelectrophilic protonated propenoyl (H2C=CH-COH2+) and isopentenoyl ((CH3)2C=CH-COH2+) dications and their parent cations were calculated using ab initio methods at the MP2/6-311+G and MP2/cc-pVTZ levels. Energies were calculated using Gaussian-2 (G2) theory. The alpha-carbon (Calpha) protonated 3 and 7 were found to be the global minima for protonated propenoyl and isopentenoyl dications, respectively.

Oxygenation of alkane C-H bonds with methyl(trifluoromethyl)dioxirane: effect of the substituents and the solvent on the reaction rate.

[Chemical reaction: See text] The mechanism of the oxygenation of alkane C-H bonds with methyl(trifluoromethyl)dioxirane (1a) is studied through the effect of the substituent and solvent on the rate of oxygenation of 2-substituted adamantanes (2). The results suggest a remarkable electron deficiency at the reacting carbon atom in the transition state leading to the regular oxygenation products. The linearity of the Hammett plot reveals that the reaction mechanism does not change within a range of 0.