- Photoinduced Molecular Transformations. Part 154. On the Mechanism of the Formation of the 5-Iodopentyl Formate in the Photolysis of Cyclopentanol Hypoiodite in Solution in the Presence of Mercury(II) Oxide-Iodine.
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(18)O-labelling experiments established that the formation of 5-iodopentyl formate in the photolysis of cyclopentanol hypoiodite in the presence of excess mercury(II) oxide-iodine in benzene involves the following pathway: a) a β-scission of a cyclopentyloxy radical to rearrange to a primary 5-oxopentyl radical, which generates the corresponding carbocation by a metal ionassisted one-electron oxidation; b) an intramolecular addition of the 5-oxopentyl cation to the formyl oxygen to generate a tetrahydropyranyl cation; c) a combination of the tetrahydropyranyl cation with diiodine oxide (I2O) to form a lactol hypoiodite; d) generation of a carbon-centred radical by a selective β-scission of a carbon-carbon bond of an alkoxyl radical generated from the lactol hypoiodite; e) abstraction of an iodine by the carbon-centred radical from an iodine molecule to form the 5-iodopentyl formate. 5-Iodopentyl formate is also produced by prolonged irradiation of a solution of 5-iodopentanal in the presence of mercury(II) oxide and iodine in benzene with Pyrex-filtered light.The formate in this case should be formed through the generation of the 5-oxopentyl cation (mentioned above) by mercury-assisted ionization of its carbon-iodine bond, followed by the same pathway as that mentioned above.
- Suginome, Hiroshi,Senboku, Hisanori
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- Synthesis of dl-9(O)-methano-Δ6-prostaglandin I1
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Biologically interesting 9(O)-methano-Δ6-prostaglandin I1 (9(O)-methano-Δ6-PGI1), a chemically stable analog of prostacyclin (PGI2), was efficiently synthesized from 1,3-cyclooctadiene with high stereo- and regiochemical control. In all three biological test systems examined, 9(O)-methano-Δ6-PGI1 was found to be considerably less active than prostaglandin E1 (PGE1).
- Iseki,Mase,Okazaki,et al.
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- Cleavage of Carboxylic Esters by Aluminum and Iodine
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A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
- Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
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p. 4254 - 4261
(2021/03/09)
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- Efficient Synthesis of ω-[18F]Fluoroaliphatic Carboxylic Esters and Acids for Positron Emission Tomography
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[18F]Fluoroaliphatic carboxylic acids are important PET tracers that have demonstrated a considerable potential to address the fatty acid oxidation-dependent processes in clinical patients. Herein, we report an efficient radiosynthetic approach to ω-[18F]fluoroaliphatic carboxylic esters and acids by nucleophilic radiofluorination of the readily available iodocarboxylic esters. Methyl 6-[18F]fluorohexanoate was further applied as a starting material for the preparation of the succinimide ester (NHS ester)-containing bifunctional radiofluorinated prosthetic group in two simple steps, 10 min each. The synthesized NHS ester of 6-[18F]fluorohexanoic acid can serve as an important reagent for a quick and efficient conjugation with peptides or proteins via amino groups of lysines.
- Belousov, Mikhail V.,Larkina, Mariia S.,Ozerskaya, Anastasia V.,Podrezova, Ekaterina V.,Tolmachev, Vladimir,Yusubov, Mekhman S.,Zhdankin, Viktor V.
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p. 6375 - 6381
(2020/10/20)
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- Expedient synthesis of long-chain ω-substituted fatty acids and esters from cyclic ketones using iodine and hydrogen peroxide
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A simple and convenient synthesis of ω-iodoaliphatic carboxylic acids and esters by the reaction of cyclic ketones with iodine and hydrogen peroxide in the presence of catalytic CuCl has been developed. ω-Iodoaliphatic carboxylic esters were further used for the efficient preparation of di(2-pyridylmethylamino)alkanoic acids in excellent yields.
- Podrezova, Ekaterina V.,Larkina, Maria S.,Belousov, Mikhail V.,Kirschning, Andreas,Zhdankin, Viktor V.,Yusubov, Mekhman S.
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p. 4081 - 4088
(2018/10/15)
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- CHELATING COMPOUNDS AND IMMOBILIZED TETHERED CHELATORS
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Novel di- and tripodal compounds useful as chelators, intermediates for their production and a method for treating an aqueous solution to remove trivalent metal ions are presented.
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- Progressive-convergent elucidation of stereochemistry in complex polyols. The absolute configuration of (-)-sagittamide A
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The absolute stereostructure of sagittamide A (1), a O-hexacetyl long-chain hexahydroxy-α,ω-dicarboxylic acid, was assigned using a progressive-convergent approach that integrates three powerful regimens for stereochemical analysis of acyclic natural prod
- Lievens, Sarah C.,Molinski, Tadeusz F.
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p. 11764 - 11765
(2007/10/03)
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- Facile synthesis of (+)-biotin via Fukuyama coupling reaction
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Treatment of a thiolactone 2 with a zinc reagent 3 in the presence of PdCl2(PPh3)2 (10 mol%) allowed installation of a C-2 side chain of (+)- biotin in a highly efficient manner, which enabled synthesis of (+)biotin in three steps from 2. (C) 2000 Elsevier Science Ltd.
- Shimizu, Toshiaki,Seki, Masahiko
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p. 5099 - 5101
(2007/10/03)
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- CONTROLLING STEREOCHEMISTRY IN RADICAL ADDITION AND CYCLIZATION REACTIONS WITH OPPOLZER'S CAMPHOR SULTAM
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Acrylate derivatives of Oppolzer's camphor sultam exhibit good to excellent levels of stereoselectivity in typical radical allylations and alkene and alkyne cyclizations.
- Curran, Dennis P.,Shen, Wang,Zhang, Jiancun,Gieb, Steven J.,Lin, Chien-Hsing
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p. 1773 - 1788
(2007/10/02)
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- LACTONIZATION REACTIONS OF (Ω-CARBOXYALKYL)SULFONIUM SALTS
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The intramolecular cyclizations of sulfonium salts having an ω-carboxyalkyl group were investigated for the synthesis of five- to nine-membered lactones, and five- to seven-membered lactones were obtained in good yields from S-(ω-carboxyalkyl)thiolanium salts.The scope and limitations of the synthetic utility of the reaction are indicated by this study. Key words: Lactonization reactions; (ω-carboxyalkyl)diphenylsulfonium salts; S-(ω-carboxyalkyl)thiolanium salts; medium-sized lactones; large-sized lactones; sulfur-containing lactones.
- Nakamura, Takako,Matsuyama, Haruo,Takahashi, Masaya,Kamigata, Nobumasa
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- Reactions of hydriodic acid with aldonolactones and n-alkanolactones. Interconversions between lactones and iodocarboxylic acids
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Aldonolactones containing from four to eight carbon atoms, and lactones of the related monohydroxy-n-alkanoic acids, were subjected to reaction with 57 percent hydriodic acid at 125 deg C.As in the classical studies of Kiliani, the reduction of D-glycero-D-ido-heptono-1,4-lactone yielded mainly γ-heptanolactone.Analogously, the corresponding γ-alkanolactones were obtained as major products from the 1,4-lactones of the D-xylono, D-allono-, and D-erythro-L-talo-octono configuration.Monoiodo-n-alkanoic acids were also formed in admixture with the lactones in all of these reactions.D-Erythrono-1,4-lactone was unique among the aldonolactones in that it led only to an acid, i.e., 3-iodo-n-butanoic acid.The latter was also the product of the non-reductive reaction of hydriodic acid with β-butyrolactone whereas, by contrast, γ-butyrolactone afforded 4-iodobutanoic acid.Among compounds in the five to eight carbon series, it was found that under conditions close to equilibrium the ratio of lactone to iodoacid decreased progressively with the length of the carbon chain; e.g., in the 4 h reactions of γ-valero, γ-capro, γ-heptano,- and γ-octanolactone, the ratios were 2.4, 1.2, 0.2, and 0.1, respectively.An accompanying characteristic of these reactions is a progression in the number of isomeric iodoacids formed.Whereas γ-valerolactone was accompanied by 4-iodopentanoic acid, there were two isomers (4- and 5-) of iodohexanoic acid, three monoiodo- (including 6-iodo-) heptanoic acids, and four (including 7-iodo-) octanoic acids.In all instances, the isomer substituted at the penultimate carbon was major.An interplay of several individual reactions, including ring-opening displacements, eliminations-additions, and rearrangements, as well as a probable influence of entropy changes on the lactone-acid equilibria, appear to account largely for these observations.
- Liu, Zhengchun,Granata, Alessandro,Shen, Xinhua,Perlin, Arthur S.
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p. 2081 - 2088
(2007/10/02)
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- 3-Trehalosamine compounds
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Novel antibiotic 3-trehalosamine (U-59,834) producible in a fermentation under controlled conditions using the new microorganism Nocardiopsis trehalosei sp. nov., NRRL 12026. This antibiotic is active against Gram-positive bacteria, for example, Staphylococcus aureus, Bacillus subtilis, and Diplococcus pneumoniae. Thus, 3-trehalosamine can be used in various environments to eradicate or control such bacteria. Antibiotic 3-trehalosamine can be shown by the following structural formula: STR1
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- Preparation of Macrocyclic Lactones by Ring Closure of Cesium Carboxylates
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A series of ω-halo fatty acids, the longest being 16-iodohexadecanoic acid, was prepared by oxidation of the corresponding ketones with m-chloroperbenzoic acid in boiling chloroform, followed by ring opening usually with hydrogen iodide in acetic acid at 100 deg C.Solutions of these acids in dimethylformamide (DMF) at concentrations of 5E-3 - 5E-2 M were treated with an equivalent amount of dry Cs2CO3.The solutions were stirred at 40 deg C overnight.Workup of the reaction mixture produced a mixture of (macro)cyclic lactone (macrolide) and its dimer (dilide).For the case of 16-iodohexanoic acid the lactone was isolated in 85percent yield.Yields for other large ring macrolides were also excellent.It was demonstrated that substitution by carboxylate on a secondary halide also goes well to afford the corresponding macrolide with no detectable amount of elimination.The effects of ring size, concentration, and solvent on the ring closure of the cesium carboxylates formed in situ were investigated.DMF is the best solvent of those investigated for the ring closure.Cesium carboxylates also undergo more readily ring closure and in far better yield than the carboxylates of lithium, sodium, potassium, rubidium, silver, thallium, magnesium, strontium, or barium.The S-lactone of ricinelaidic acid was prepared optically pure in 80percent yield from optically pure mesylate of R-ricinelaidic acid, which was treated with cesium carbonate in dry DMF.This demonstrates that the ring closure proceeds with the anticipated SN2 inversion at the hydroxyl-bearing carbon atom.With the same approach optically pure S-zearalenone was protected and subjected to ring opening, and the hydroxyl group was activated as mesylate.Some racemization was found to occur in the ring-opening step.On treatment of this material with dry cesium carbonate in DMF, the desired ring closure took place in 80percent yield to provide an excess of the protected R enantiomer of zearalenone.On the basis of these results, some speculations are made concerning the action of cesium in promoting ring closure to macrocyclic lactones.
- Kruizinga, Wim H.,Kellogg, Richard M.
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p. 5183 - 5189
(2007/10/02)
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- Antibiotic 354 and process for producing same
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Novel antibiotic 354 (U-54,703) producible in a fermentation under controlled conditions using the new microorganism Streptomyces puniceus subsp. doliceus, NRRL 11160. This antibiotic is active against Gram-negative bacteria, for example, Pseudomonas and Proteus species. Thus, antibiotic 354 can be used in various environments to eradicate or control such bacteria.
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- Composition of matter and process
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Novel antibiotic formulations of antibiotic 354 (U-54,703) and their use in treating susceptible infectious disease in humans and animals.
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- Aminoglycoside antibiotics
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6-0- AND 3'-0-D-glycosyl analogs of 4-0-(α-D-glycosyl)-2-deoxystreptamine, 6-0- and 3'-0-D-glycosyl ortho esters of 4-0-(α-D-glycosyl)-2-deoxystreptamine, novel aminoglycoside antibiotics, and novel intermediates are prepared by a new chemical process. The compounds have utility as antibacterial agents or as intermediates to make antibacterially-active compounds.
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