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PubMed2000

catena-Poly[[diaqualithium(I)]-mu-[9H-purine-2,6(1H, 3H)-dionato-O2:N7]].

In the title compound, [Li(C(5)H(3)N(4)O(2))(H(2)O)(2)](n), the coordinate geometry about the Li(+) ion is distorted tetrahedral and the Li(+) ion is bonded to N and O atoms of adjacent ligand molecules forming an infinite polymeric chain with Li-O and Li-N bond lengths of 1.901 (5) and 2.043 (6) A, respectively. Tetrahedral coordination at the Li(+) ion is completed by two cis water molecules [Li-O 1.985 (6) and 1.946 (6) A]. The crystal structure is stabilized both by the polymeric structure and by a hydrogen-bond network involving N-H.O, O-H.O and O-H.N hydrogen bonds.

Chelating Agents↗
PubMed2004

Formulation of sustained - release lithium carbonate matrix tablets: influence of hydrophilic materials on the release rate and in vitro-in vivo evaluation.

PURPOSE: Conventional lithium carbonate (LC) tablets not only produce rapid and relatively high peak blood levels resulting in adverse effects but also should be administered 3 to 4 times daily. These drawbacks can be overcome by designing a suitable sustained-release LC preparation. METHODS: Sustained-release matrix tablets containing 450 mg LC were developed using different types and ratios of polymers including carbopol (CP), Na carboxymethylcellulose (Na CMC) and hydroxypropylmethylcellulose (HPMC). The tablets were prepared by either direct compression or wet granulation. In vitro and in vivo, newly formulated sustained-release LC tablets were compared with sustained-release commercial tablet (Eskalith CR). In vivo studies were conducted in nine healthy subjects in a cross over design, with a 3 3 Latin square sequence. Pharmacokinetic parameters were estimated using classical methods. RESULTS: The matrix tablets containing 15% CP exhibited suitable release kinetics and uniform absorption characteristics comparable to that of Eskalith CR. In vivo, this formulation produced a smooth and extended absorption phase very much similar to that of Eskalith CR with the identical elimination half-life and extent of absorption. CONCLUSION: In vitro release studies demonstrated that the releases of LC from all formulated sustained matrix tablets were generally sustained. Na CMC, CP, and HPMC can, therefore, be used to modify release rates of LC in hydrophilic matrix tablets. The sustained release behavior of tablets containing 15% CP prevents high peak blood levels in man and could be given twice daily to promote patient compliance during maintenance therapy.

Adult↗
PubMed2000

Lithium, Sodium, and Copper(I) Supersilylphosphanediides M(2)PSitBu(3): Compounds with Novel Spherical (M(2)P)(n) Frameworks Compounds of Silicon, Part 133; Supersilyl Compounds of Phosphorus, Part 6. This work was supported by the Deutsche Forschungsgemeinschaft and by the Fonds der Chemischen Industrie. Part 132: N. Wiberg, T. Passler, S. Wagner, J. Organomet. Chem. 2000, 598/2, 304; Part 5: N. Wiberg, A. Wörner, H.-W. Lerner, K. Karaghiosoff, H. Nöth, Z. Naturforsch. B 1998, 53, 1004.

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Journal Article↗
PubMed2007

Mechanistic study on rearrangement cascades starting from annulated 2-aza-hepta-2,4-dienyl-6-ynyl anions: formation of aniline and azepine derivatives.

Deprotonation of benzothiophene-derived alkynyl imine 11 with lithium diisopropylamide (LDA) and subsequent transmetalation with ZnCl2 etherate furnished azepine 12 upon aqueous workup. Similarly, alkynyl benzaldimine 1a gave a mixture of benzazepine 13 and naphthylamine 14. Allylic benzonitriles 15 a,b reacted to produce naphthylamine 16 upon deprotonation with LDA at room temperature. In an analogous manner, imino benzonitrile 17 may be converted into 4-amino isoquinoline 18 by means of an intramolecular nucleophilic attack on the nitrile function upon treatment with LDA. The allylic benzonitriles 19 a,b were prepared by LDA treatment of alkynyl imine 11. They were further converted to amino dibenzothiophene 20 by LDA deprotonation and aqueous workup. These various transformations represent the key steps of a multistep reaction cascade, which was previously postulated on the basis of quantum chemical calculations. Thus, all features of this complex rearrangement mechanism could now be confirmed experimentally. DFT calculations support the lower reactivity of zinc species in the ring-opening step compared to the lithium intermediates. All new compounds were completely characterized by spectroscopic data, including X-ray diffraction studies for the key compounds 12, 19 a, and 20.

Journal Article↗
PubMed1983

Antitumor agents LXII: synthesis and biological evaluation of podophyllotoxin esters and related derivatives.

Synthetic esters of the C-4 hydroxyl group of podophyllotoxin (I) were prepared. In addition, esters were synthesized using the diol system of tetrahydropyranyl podophyllol (XV), produced by reducing the lactone ring of tetrahydropyranyl podophyllotoxin with lithium aluminum hydride. Six compounds, the acrylate (IV), 3,3-dimethyl acrylate (V), phenoxyacetate (IX), and ethyl adipate (XI) of I as well as podophyllol (XIV) and tetrahydropyranyl podophyllol dimesylate (XVIII), showed significant activity when tested using the P-388 lymphocytic leukemia screen at 3 mg/kg/day. None of the esters showed higher activity than that shown by the parent molecule I when tested at the same dosage level.

Animals↗
PubMed1993

Quantitative grip strength assessment as a means of evaluating muscle relaxation in mice.

The effects of various centrally acting drugs and some peripherally acting agents on the forelimb grip strength of CD-1 mice were explored. Forelimb grip strength was assessed by use of a strain gauge to measure the lateral pull force, in grams, exerted by mice as an index of muscle relaxation. The muscle relaxants, diazepam, midazolam, baclofen, methocarbamol, dantrolene sodium and the neuromuscular blocking agents, succinylcholine and pancuronium bromide, dose-dependently reduced forelimb grip strength. 2-Amino-7-phosphonoheptanoic acid (AP7), which has also been shown to have muscle relaxant effects, also reduced grip strength. Pentobarbital, ethanol, phencyclidine, ketamine and chlorpromazine reduced grip strength at doses which produced behavioral impairments. Lithium chloride, a toxic compound used to induce taste aversions, and clonidine, at doses which affect blood pressure, body temperature and locomotor activity, did not affect grip strength. In addition, stimulant doses of amphetamine and caffeine, but not of morphine, increased grip strength in a dose-dependent manner. These results extend previous findings and suggest that this forelimb grip strength procedure may be a useful screening test for the identification of the potential muscle relaxant properties of drugs.

Animals↗
PubMed2003

Differential pulse anodic voltammetric determination of lithium ions in pharmaceutical formulations using a carbon paste electrode modified with spinel-type manganese oxide.

The use of the differential pulse voltammetry for the determination of lithium ions in pharmaceutical samples using a carbon paste electrode modified with spinel-type manganese oxide has been examined. The best voltammetric response was reached for a modified electrode in borate buffer solution of pH 9.0 and submitted to a scan rate of 5 mV s(-1) and a pulse amplitude of 50 mV. This electroanalytical procedure was able to determine lithium ions in the concentration range of 8.0 x 10(-5)-1.0 x 10(-2) mol l(-1) even in the presence of several alkali metals (1.0 x 10(-3) mol l(-1)) with a detection limit of 7.1 x 10(-7) mol l(-1). Rapidity, precise and good selectivity were also found for the determination of lithium ions in pharmaceutical formulations.

Calibration↗
PubMed2002

Solid-phase C-C and C-O bond forming reactions using 'traceless' pi-arene-chromium linkers.

The scope of solid-phase reactions utilizing a 'traceless' pi-arene-chromium linker has been expanded to include the addition of organo-lithium reagents to a supported ester group, generation and alkylation of an enolate anion, and substitution via the Mitsunobu reaction. Immobilization of ortho-disubstituted polyfunctionalized arene chromium dicarbonyl species onto the solid support and subsequent, selective transformation is also reported.

Anions↗
PubMed2006

Low-temperature synthesis of alpha-MnO2 hollow urchins and their application in rechargeable Li+ batteries.

Novel alpha-MnO2 hollow urchins were synthesized on a large scale by a facile and efficient low-temperature (60 degrees C) mild reduction route, without templates or surfactants in the system. The formation mechanism for the hollow urchins was proved to be the Ostwald ripening process by tracking the crystallization and morphology of the product at different reaction stages. The as-prepared hollow-urchin sample has a high Brunauer-Emmett-Teller surface area of 132 m(2)/g and a mesoporous structure, which were expected to help improve the electrochemical property in Li+ batteries. When the alpha-MnO2 hollow urchins were used as the cathode material in Li batteries, they performed better than the other alpha-MnO2 samples (solid urchins and dispersed nanorods), indicating that the electrochemical performance of the electrode material is sensitive to its morphology. This synthetic procedure is straightforward and inexpensive and thus facilitates mass production of alpha-MnO2 hollow urchins.

Cold Temperature↗
PubMed2002

Asymmetric carbon-carbon bond formations in conjugate additions of lithiated N-Boc allylic and benzylic amines to nitroalkenes: enantioselective synthesis of substituted piperidines, pyrrolidines, and pyrimidinones.

(-)-Sparteine mediated lithiations of N-Boc-allylic and benzylic amines provide configurationally stable intermediates which on conjugate additions to nitroalkenes provide highly enantioenriched enecarbamate products in good yields, and with high diastereoselectivities. Straightforward transformations of these adducts offer general routes to substituted 3,4-substituted piperidines, 3,4-substituted pyrrolidines, and 4,5-substituted pyrimidinones. Diastereoselective substitutions of intermediate lactams followed by reduction provide 3,4,5-substituted piperidines and 3,4-trisubstituted pyrrolidines. Lithiation adjacent to nitrogen of 3,4-substituted piperidines and pyrrolidines followed by diastereoselective substitution opens a route to 2,4,5- and 2,4,5,6-substituted piperidines as well as 2,3,4- and 2,3,4,5-substituted pyrrolidines. The enantiomers of the enecarbamate and 3,4-substituted piperidine products may be accessed by stannylation/transmetalation sequences as well as by further manipulation of 4-substituted piperidones. The methodology is used to synthesize both enantiomers of an aspartic peptidase inhibitor intermediate, 3-hydroxy-4-phenylpiperidine, as well as the antidepressant (+)-femoxetine.

Alkenes↗
PubMed2004

Construction of arene-fused-piperidine motifs by asymmetric addition of 2-trityloxymethylaryllithiums to nitroalkenes: the asymmetric synthesis of a dopamine D1 full agonist, A-86929.

The straightforward methodology for the construction of chiral arene-fused-piperidine motifs using a highly enantioselective addition of 2-trityloxymethylaryllithiums to cyclic and acyclic nitroalkenes has been developed. The versatility of the process was highlighted by the first asymmetric synthesis of a dopamine D1 full agonist, A-86929.

Alkenes↗
PubMed2003

New organolithium addition methodology to diversely functionalized indoles.

A novel synthetic approach to diversely functionalized indoles is described. Boc-protected ortho-aminostyrenes undergo an alkyllithium addition reaction, thereby generating a lithiated intermediate, which upon reaction with specific electrophiles sets up a cascade reaction process between the reacted electrophile and ortho-amino substituent, facilitating an in situ ring closure, followed by dehydration, to generate an indole ring system. This methodology is demonstrated by the synthesis of a range of 3,5-, 1,3,5-, and 2,3,5-substituted indoles.

Indoles↗
PubMed2003

Heterobimetallic catalysis in asymmetric 1,4-addition of O-alkylhydroxylamine to enones.

A heterobimetallic YLi3tris(binaphthoxide) catalyst (YLB) promoted a 1,4-addition of O-methylhydroxylamine in high enantiomeric excess (up to 97% ee). Catalyst loading was reduced to as little as 0.5 mol %, still affording the 1,4-adduct in 96% yield and 96% ee. A high concentration of substrates and the scalability of the present system is also practically useful. The results suggested that the heterobimetallic catalysis was not deactivated even in the presence of excess amine under highly concentrated conditions. A Y and Li bimetallic cooperative function was essential for a high catalyst turnover number.

Alkenes↗
PubMed2004

Density functional theory studies on the mechanisms of regioselective allylic and cis-vinylic deprotonation of allyl amides and allylamines.

A density functional theory (B3LYP/6-31+G) study was undertaken in an effort to learn more about the mechanisms controlling the regioselective deprotonations of the synthetically versatile N-lithio-N-(tert-butyl)allylamide 1 and N-lithio-N-(trimethylsilyl)allylamine 2 compounds. The calculations suggest that deprotonation of 1 occurs exclusively at the allylic position. This agrees with experimental results. The calculations also suggest that deprotonation of allylamine 2 exclusively at the cis-vinylic position is due to kinetic control.

Allyl Compounds↗