- One-pot synthesis of α-bromo- and α-azidoketones from olefins by catalytic oxidation with in situ-generated modified IBX as the key reaction
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Simple one-pot protocols for the syntheses of α-bromoketones and α-azidoketones starting from olefins have been developed by employing catalytic oxidation of the intermediary bromohydrins with in situ-generated modified IBX as the key reaction. The improved procedure involves initial formation of bromohydrin by the reaction of olefin with NBS in acetonitrile-water mixture (1:1) at rt followed by oxidation with in situ-generated 3,4,5,6-tetramethyl-2-iodoxybenzoic acid (TetMe-IBX), produced in catalytic amounts from 3,4,5,6-tetramethyl-2-iodobenzoic and Oxone. α-Bromoketones are further converted in the same pot to the corresponding α-azidoketones using NaN3/NaHCO3. The one-pot conversions are versatile for a variety of olefins that include cyclic as well as acyclic aliphatic olefins and electron-rich and electron-deficient styrenes. Chemoselective bromohydroxylation of electron-rich double bond and subsequent oxidation to the α-bromoketone is demonstrated for a substrate that contains both electron-rich and deficient double bonds.
- Chandra, Ajeet,Parida, Keshaba Nanda,Moorthy, Jarugu Narasimha
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p. 5827 - 5832
(2017/09/09)
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- Catalytic dehydrogenative dual functionalization of ethers: Dealkylation-oxidation-bromination accompanied by C-O bond cleavage: Via aerobic oxidation of bromide
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Catalytic dehydrogenative dual functionalization (DDF) of ethers via oxidation, dealkylation, and α-bromination by the aerobic oxidation of bromide was developed to obtain the corresponding α-bromo ketones in high yields. In particular, the reaction of substituted tetrahydrofurans as cyclic ethers provided 3,3-dibromo tetrahydrofuran-2-ols in high yields selectively through the double α-bromination.
- Moriyama, Katsuhiko,Hamada, Tsukasa,Nakamura, Yu,Togo, Hideo
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supporting information
p. 6565 - 6568
(2017/07/10)
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- A Simple and Efficient Method for the Preparation of α-Halogenated Ketones Using Iron(III) Chloride and Iron(III) Bromide as Halogen Sources with Phenyliodonium Diacetate as Oxidant
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α-Halogenated ketones are both unique structure moieties existing in biologically natural products and valuable synthetic intermediates for the preparation of functional molecules. An efficient and scalable method for the preparation of α-halogenated ketone using iron (III) chloride and iron (III) bromide as halogen sources with phenyliodonium diacetate as oxidant has been developed, featuring mild reaction conditions, environmentally friendly reagents, and wide substrate scope. Notably, the three-step synthesis of drug prasugrel was achieved using this developed method as a key step with 30% yield on gram-scale. Additionally, the reaction mechanism involving chloride cation was proposed based on some preliminary control experiments. (Figure presented.).
- Tang, Shi-Zhong,Zhao, Wenshuang,Chen, Tao,Liu, Yang,Zhang, Xiao-Ming,Zhang, Fu-Min
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supporting information
p. 4177 - 4183
(2017/12/18)
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- Oxidative debenzylation of N-benzyl amides and O-benzyl ethers using alkali metal bromide
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The oxidative debenzylation of N-benzyl amides and O-benzyl ethers was promoted with high efficiency by a bromo radical formed through the oxidation of bromide from alkali metal bromide under mild conditions. This reaction provided the corresponding amides from N-benzyl amides and carbonyl compounds from O-benzyl ethers in high yields.
- Moriyama, Katsuhiko,Nakamura, Yu,Togo, Hideo
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supporting information
p. 3812 - 3815
(2014/08/05)
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- Halogen and chalcogen cation pools stabilized by DMSO. Versatile reagents for alkene difunctionalization
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Halogen and chalcogen cations (X+ = Br+, I +, ArS+, and ArSe+) were generated by low-temperature electrochemical oxidation in the presence of dimethyl sulfoxide (DMSO) and were accumulated in the solution. DFT calculations indicated that DMSO stabilizes these cations by coordination. The complexes of I+ with one and two DMSO molecules were observed by cold-spray-ionization MS analyses. The stability of the resulting cation pools of X+ increased in the order of Br+ + + +, which could be explained in terms of the electronegativity of X. The cation pools served as versatile reagents for organic synthesis; the reactions with alkenes gave β-X-substituted alkoxysulfonium ions, which were converted to the corresponding carbonyl compounds by the treatment with triethylamine, whereas the treatment with methanol gave the corresponding alcohols. The reactions with aminoalkenes and 1,6-dienes gave the cyclized products.
- Ashikari, Yosuke,Shimizu, Akihiro,Nokami, Toshiki,Yoshida, Jun-Ichi
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supporting information
p. 16070 - 16073
(2013/11/19)
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- Synthesis of quinoxaline analogues
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Substituted tricyclic or tetracyclic quinoxalines, tricyclic pyridoquinoxalines and bis-quinoxalines were synthesized in high yields starting from cyclic ketones by the -bromination of cyclic ketones with N-bromosuccinimide (NBS) followed by condensation of the resulting -bromo ketones with 1,2-diaminobenzene, 3,4-diaminopyridine, or 3,3-diaminobenzidine. Georg Thieme Verlag Stuttgart New York.
- Chang, Meng-Yang,Lee, Tein-Wei,Hsu, Ru-Ting,Yen, Tzu-Lin
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experimental part
p. 3143 - 3151
(2011/10/30)
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- A family of thiazolium salt derived N-heterocyclic carbenes (NHCs) for organocatalysis: Synthesis, investigation and application in cross-benzoin condensation
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A family of thiazolium salt derived N-heterocyclic carbenes (NHCs) bearing sterically demanding aryl substituents on the nitrogen and with varying backbone substitution patterns have been synthesized. Investigation of the catalytic activity of these NHCs in a number of benzoin-type coupling reactions revealed markedly different levels of reactivity and selectivity. To elucidate the underlying factors leading to differences in reactivity, a study of the electronic and steric properties of these NHC catalysts was conducted. By using the best catalyst in this study, the intermolecular cross-benzoin condensation reaction was explored in more detail.
- Piel, Isabel,Pawelczyk, Marius D.,Hirano, Keiichi,Froehlich, Roland,Glorius, Frank
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supporting information; experimental part
p. 5475 - 5484
(2011/11/29)
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- Photochemical α-bromination of ketones using N-bromosuccinimide: a simple, mild and efficient method
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Aromatic and aliphatic carbonyl compounds undergo facile bromination with N-bromosuccinimide under UV-vis irradiation to give the corresponding α-brominated ketones in good yields, at low temperatures (30 °C), without any catalyst, catalyst support or radical initiator and within a short time.
- Arbuj, Sudhir S.,Waghmode, Suresh B.,Ramaswamy
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p. 1411 - 1415
(2007/10/03)
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- On Triazoles XXXI. The Reaction of 1,2,4-Triazolylcarbothiohydrazides with Homo- and Heterocyclic Ketones. An Unexpected Reaction Leading to 4,5-Polyalkylene Thiazoles
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The reaction of 1,2,4-triazolylcarbothiohydrazides with homo- and heterocyclic ketones to yield 8-spirotriazolotetrazepine-5-thiones 7 (n = 4, 5, 6, 7 and 11), 8 and 9, respectively, all representing movel ring systems was studied.Providing the reaction at higher temperature a novel reaction was observed to yield 4,5-polyalkylene thiazoles for which a mechanism is proposed.
- Barkoczy, Jozsef,Szabo, Eva,Reiter, Jozsef
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p. 1019 - 1024
(2007/10/02)
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- Reaction of Organic Halides with Chlorotris(triphenylphosphine)cobalt(I)
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Reaction of various types of organic halides with a monovalent cobalt complex, chlorotris(triphenylphosphine)cobalt(I) is described.Reaction of benzylic monohalides, dihalides and trihalides with CoCl(Ph3P)3 gave a coupling product with formation of a carbon-carbon single bond, double bond and triple bond, respectively, under mild and non-basic conditions.Dehalogenation of non-benzylic vicinal dihalides with the reagent took place cleanly to give an olefin in high yield.Reductive coupling of allylic halides using the reagent afforded regioselectively a 1,5-diene with retention of the stereochemistry of the carbon-carbon double bond of the allylic halides used.By using this reaction, (E,E,E,E)-squalene was stereospecifically synthesized from (E,E)-farnesyl bromide.Reaction of halohydrins with CoCl(Ph3P)3 gave exclusively a ketone in the presence of an amine or olefin through an alkylcobalt intermediate.A 1,2-hydrogen shift is involved in this reaction.Keywords - chlorotris(triphenylphosphine)cobalt(I); coupling reaction; benzylic halides; allylic halides; synthesis of 1,5-diene; squalene; halohydrin; ketone synthesis.
- Momose, Den-ichi,Iguchi, Kazuo,Sugiyama, Toshikazu,Yamada, Yasuji
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p. 1840 - 1853
(2007/10/02)
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- Preparation of 13-oxabicyclo[10.3.0]pentadecane
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This invention relates to the preparation of 13-oxabicyclo[10.3.0]pentadecane. More specifically, this invention relates to a process for preparing 13-oxabicyclo[10.3.0]pentadecane which comprises the steps of: (a) reacting cyclododecanone with elemental bromine in an organic solvent to form α-bromocyclododecanone; (b) reacting α-bromocyclododecanone with malonic acid dialkyl ester and alkali metal alcoholate to form the ketodiester 2-(2-oxocyclododec-1-yl)-malonic acid dialkyl ester; (c) hydrolyzing and decarboxylating the ketodiester from step (b) to from the corresponding 2-oxocyclododec-1-yl-acetic acid in an aqueous alkaline solution; (d) purifying the product of step (c) by extraction with an organic solvent and obtaining 2-oxocyclododec-1-yl-acetic acid; (e) reacting the product of step (d) with a lower alcohol to form a corresponding ester; (f) reducing the product of step (e) with a complex metallic hydride to form 2-(2-hydroxyethyl)-cyclododecanol; and (g) heating the product of step (f) in the presence of an acid catalyst to form 13-oxabicyclo[10.3.0]pentadecane.
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