- Aziridines as templates: A general strategy for the stereospecific synthesis of 2-azetidinones
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Various routes to a variety of azridine-2-carboxylates have been described and the stereochemistry of these compounds has been determined by spectroscopic methods. Further, greater diversity of β-lactams via ring expansion of these azridines-2-carboxylates were obtained by a general, efficient and direct stereospecific approach.
- Sharma,Kanwar, Seema,Rajpoot, Shivani
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- A radical based addition-elimination route for the preparation of indoles
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Indoles, including tricyclic derivatives, are produced by cyclisations of aryl radicals onto vinyl halides followed by elimination of halide radical and tautomerism of the resulting product; the aryl radicals are produced using "clean methodology" either by reaction of iodide ions with arenediazonium salts or by reaction of phosphorus-centred radicals with aryl iodides. The Royal Society of Chemistry 2000.
- Murphy, John A.,Scott, Karen A.,Sinclair, Rhoha S.,Martin, Concepcion Gonzalez,Kennedy, Alan R.,Lewis, Norman
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p. 2395 - 2408
(2007/10/03)
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- Carbonylation of silylated hydroxymethyl aziridines to β-lactams
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Functionalized β-lactams are synthesized by carbonylative ring expansion of silylated hydroxymethyl aziridines catalyzed by dicobalt octacarbonyl, a process that proceeds with inversion of configuration. Ring opening and elimination occurs on attempted carbonylation of aziridine carboxylates.
- Davoli, Paolo,Moretti, Irene,Prati, Fabio,Alper, Howard
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p. 518 - 521
(2007/10/03)
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- A new synthesis of indoles
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Aryl radical cyclisation onto appropriate vinyl bromides leads to a new route to indoles.
- Murphy, John A.,Scott, Karen A.,Sinclair, Rhona S.,Lewis, Norman
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p. 7295 - 7298
(2007/10/03)
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- Perfluorohexane as a novel reaction medium for bromination reactions
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Perfluorohexane is shown to be a good alternative to carbon tetrachloride as a non-toxic, non-ozone-depleting, inert reaction medium for bromination reactions. Yields of brominated products were nearly quantitative and the reaction work-up was easier.
- Pereira,Savage,Simpson
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p. 1023 - 1026
(2007/10/02)
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- 1,2-asymmetric induction in radical reactions. Deuteration and allylation reactions of β-oxy-α-bromo esters
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Chiral radicals were generated by halogen abstraction reactions of β-oxy-α-bromo esters and their asymmetric deuteration and allylation reactions were studied.
- Curran,Ramamoorthy
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p. 4841 - 4858
(2007/10/02)
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- An Improved Synthesis of 3-(1-Imidazolyl)-2-alkenoic Acid Derivatives and Related Compounds
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The preparative method of 3-(1-imidazolyl)-2-alkenoic acid derivatives and the related compounds was improved by the use of strong bases such as sodium hydride in DMF.By this improved method, the preparation of 2-substituted 3-(1-imidazolyl)-2-alkenoic acid derivatives was accomplished in good yields.
- Kashima, Choji,Yoshiwara, Nobutoshi,Tajima, Tadakuni,Omote, Yoshimori
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p. 1595 - 1596
(2007/10/02)
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- Tissue Distribution Properties of Technetium-99m-Diamide-Dimercaptide Complexes and Potential Use as Renal Radiopharmaceuticals
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A series of new ligands and the corresponding technetium-99m chelates based on diamide dimercaptide donor groups were synthesized as derivatives of technetium-99m 1,2-bis(2-thioacetamido)ethane, a complex shown to be excreted by renal tubular secretion. Chelation with 99mTc resulted in single radiochemical products or the expected numbers of stereoisomers. They were purified by high-performance liquid chromatography (HPLC) and evaluated in mice as potential renal tubular function agents. The in vivo properties were sensitive to the presence of functional groups, the positional isomerism of the carboxylate group functionality, and the chelate ring stereochemistry of the ligand. The presence of methyl groups slowed renal transit and decreased renal specificity. Cyclohexyl rings fused to the ethylene bridge of the center chelate ring decreased renal excretion while aromatic rings essentially abolished renal excretion. Slow hepatobiliary clearance was observed as an alternate mode of excretion. Polar groups, such as hydroxyl, carboxylate, and carboxamide, increased renal excretion rates and specificity in a stereochemically dependent manner. 99mTc chelates of 1,3-bis(2-thioacetamido)-2-hydroxypropane, 3,4-bis(2-thioacetamido)butanoate and 1,8-dimercapto-2,7-dioxo-3,6-diazanonanoate were identified as promising new renal radiopharmaceuticals.
- Kasina, Sudhakar,Fritzberg, Alan R.,Johnson, Dennis L.,Eshima, Dennis
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p. 1933 - 1940
(2007/10/02)
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- Kinetics and Mechanism of Bromine Addition to Derivatives of Unsaturated Aliphatic Carboxylic Acids in Aqueous Solution
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This paper deals with the kinetics of bromine addition to unsaturated compounds in presence of added bromide ions at 22, 30, 38, 46, and 54 deg C.The substrates used were acrylamide (AAm), methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), t-butyl acrylate (tBA), methacrylamide (MAAm), methyl methacrylate (MMA), ethyl methacrylate (EMA), methyl crotonate (MC), and ethyl crotonate (EC).The kinetics was followed potentiometrically.The activation parameters (ΔH*, ΔS*, and ΔG*) were calculated and compared.Estimation of product ratio of bromohydrin to dibromide showed the absence of any correlation of the product formation with reactivity of the substrates.The observed parameters are discussed in relation to the proposed reaction mechanisms.
- Mohamed Farook, Syed Ahamed,Viswanathan, Seshaiyer,Ganesan, Ramachandran
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p. 1394 - 1400
(2007/10/02)
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