- IODOSOBENZENE TETRAFLUOROBORATE: FIRST EXAMPLE OF A STABLE ELECTROPHILIC HYPERVALENT IODINE REAGENT WITHOUT NUCLEOPHILIC LIGANDS
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Iodosobenzene tetrafluoroborate 1 has been prepared by the reaction of PhI(OAc2) and aqueous HBF4, and its reactions with alkenes, silyl enol ethers, and acetylenes have been studied.
- Zhdankin, Viktor V.,Tykwinski, Rik,Caple, Ronald,Berglund, Bruce,Koz'min, Anatoly S.,Zefirov, Nikolai S.
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- B2pin2-Mediated Palladium-Catalyzed Diacetoxylation of Aryl Alkenes with O2 as Oxygen Source and Sole Oxidant
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A novel palladium-catalyzed alkene diacetoxylation with dioxygen (O2) as both the sole oxidant and oxygen source is developed, which was identified by 18O-isotope labeling studies. Control experiments suggested that bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation of a C-O bond. This method performed good functional group tolerance with moderate to excellent yields, which could be successfully applied to the late-stage modification of natural products. Furthermore, an atmospheric pressure of dioxygen enhances the practicability of the protocol.
- Huang, Jiuzhong,Ouyang, Lu,Li, Jianxiao,Zheng, Jia,Yan, Wuxin,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 5090 - 5093
(2018/09/12)
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- Metal-free, organocatalytic syn diacetoxylation of alkenes
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A novel method for the organocatalytic syn diacetoxylation of alkenes has been developed using aryl iodides as efficient catalysts. A broad range of substrates, including electron-rich as well as electron-deficient alkenes, are smoothly transformed by the new procedure, furnishing the desired products in good to excellent yields with high diastereoselectivity (up to >19:1 dr).
- Zhong, Wenhe,Liu, Shan,Yang, Jun,Meng, Xiangbao,Li, Zhongjun
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supporting information; experimental part
p. 3336 - 3339
(2012/08/29)
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- BF3·OEt2-promoted diastereoselective diacetoxylation of alkenes by PhI(OAc)2
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Selective syn and anti diacetoxylations of alkenes have been achieved using a PhI(OAc)2/BF3·OEt2 system in the presence and absence of water, respectively. A broad range of substrates including electron-deficient alkenes (such as α,β-unsaturated esters) could be elaborated efficiently at room temperature with this methodology, furnishing the desired products in good to excellent yields and diastereoselectivity. In particular, a multigram-scale diastereoselective diacetoxylation of methyl cinnamate (5.00 g) was also accomplished in a few hours, maintaining the same efficiency as small-scale reaction. This novel methodology provides an alternative approach for the preparation of various 1,2-diols.
- Zhong, Wenhe,Yang, Jun,Meng, Xiangbao,Li, Zhongjun
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supporting information; scheme or table
p. 9997 - 10004
(2012/02/05)
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- Efficient diacetoxylation of alkenes via Pd(II)/Pd(IV) process with peracetic acid and acetic anhydride
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A palladium-catalyzed diacetoxylation of alkenes in the presence of peracetic acid and acetic anhydride was developed to produce diacetates efficiently and diastereoselectively. Due to its mild conditions, this method was suitable for a broad range of substrates encompassing conjugated and nonconjugated olefins.
- Park, Chan Pil,Lee, Joo Ho,Yoo, Kyung Soo,Jung, Kyung Woon
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supporting information; experimental part
p. 2450 - 2452
(2010/07/05)
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- Bis(NHC)-palladium(II) complex-catalyzed dioxygenation of alkenes
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Bis(NHC)-Pd(II) complexes derived from l,l'-binaphthyl-2,2'-diamine (BINAM) were successfully first used to catalyze the dioxygenation of alkenes under mild conditions tolerant of air and moisture. Cationic NHC-Pd2+ diaquo complex 1e showed the highest catalytic activity to give 1,2dioxygenation products with good syn-diastereoselectivity for 1,2-disubstituted alkenes.
- Wang, Wenfeng,Wang, Feijun,Shi, Min
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experimental part
p. 928 - 933
(2010/05/01)
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- Palladium-catalyzed olefin dioxygenation
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A general method for the vicinal dioxygenation of olefins was developed using cationic Pd diphosphine complexes as the catalysts and PhI(OAc)2 as the terminal oxidant. In comparison to known Pd-catalyzed vicinal oxidations, this method is suitable for a broad range of olefins in both inter- and intramolecular reactions. An 18O-labeling experiment provides insight into the mechanism of this transformation which presumably involves Pd(II)/Pd(IV) intermediates. Copyright
- Li, Yang,Song, Datong,Dong, Vy M.
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p. 2962 - 2964
(2008/09/20)
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- Isolation, Characterization, and Reaction of Activated Iodosylbenzene Monomer Hydroxy(phenyl)iodonium Ion with Hypervalent Bonding: Supramolecular Complex PhI+OH·18-Crown-6 with Secondary I...O Interactions
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The isolation, characterization, and reaction of the active species hydroxy(phenyl)iodonium ion with hypervalent bonding are reported. Reaction of iodosylbenzene with HBF4-Me2O in the presence of equimolar 18-crown-6 in dichloromethane afforded the hydroxy-λ3-iodane complex PhI(OH)BF4·18-crown-6 as stable yellow prisms. X-ray structure analysis indicated that both the close contacts between the iodine(III) and the three adjacent oxygen atoms of 18-crown-6, and the hydrogen bonding OH...O(crown ether) will be responsible for the increased stability of the complex as compared to the uncomplexed PhI(OH)BF4. The crown ether complex is highly reactive and serves as a versatile oxidant even in water: thus, the complex undergoes oxidative transformations of a variety of functional groups such as olefins, alkynes, enones, silyl enol ethers, sulfides, and phenols under mild conditions. Copyright
- Ochiai, Masahito,Miyamoto, Kazunori,Shiro, Motoo,Ozawa, Tomoyuki,Yamaguchi, Kentaro
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p. 13006 - 13007
(2007/10/05)
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- Esterification of alkene with cerium(IV) sulfate in carboxylic acid
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Reaction of alkenes [cyclohexene (1), cycloheptene (2), cyclooctene (3), 1-heptene (4), 1-octene (5), styrene (6), 1,7-octadiene (7), indene (8), and 1,2-dihydronaphthalene (9)] with cerium(IV) sulfate (CS) in carboxylic acids [formic acid, acetic acid, and propionic acid] readily yielded the corresponding carboxylic esters. This addition reaction follows the Markovnikov rule. This reaction provides a new simple method for preparing carboxylic esters from alkenes. It was also found that this method is useful for formylation.
- Horiuchi, C. Akira,Fukushima, Tomoaki,Furuta, Noriyuki,Chai, Wen,Ji, Shun-Jun,Saito, Yoshikazu,Hashimoto, Chikao,Takahashi, T. Tomoyoshi,Sugiyama, Takashi,Muto, Akinori,Sakata, Yusaku,Nozaki, Sukekatsu
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p. 270 - 272
(2007/10/03)
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- Novel Carboxymethylation of Styrene Derivatives by Mn(3+)-Mediated Electrooxidation
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Anodic oxidation in a mixed solvent of acetic acid and acetic anhydride containing a variety of styrene derivatives, small amounts of Mn(OAc)2*4H2O and Cu(OAc)2*H2O brought about a facile carboxymethylation to give the corresponding γ-butyrolactones as the main products in good yields.
- Shundo, Ryushi,Nishiguchi, Ikuzo,Matsubara, Yoshiharu
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p. 185 - 188
(2007/10/02)
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- Iodosobenzene Tetrafluoroborate, Hexafluoroantimonate, and Hexafluorophosphate: Stable Electrophilic Hypervalent Iodine Reagents without Nucleophilic Ligands
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Three novel iodine(III) derivatives - tetrafluoroborate (1), hexafluoroantimonate (2), and hexafluorophosphate (3) - were prepared by the reaction of (diacetoxyiodo)benzene with aqueous solutions of the corresponding acids.Reactions of these reagents with
- Zhdankin, Viktor V.,Tykwinski, Rik,Berglund, Bruce,Mullikin, Michelle,Caple, Ronald,et al.
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p. 2609 - 2612
(2007/10/02)
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- Mechanisms for Manganese(III) Osidations with Alkenes
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In the reaction of manganese(III) acetate with carboxylic acids and alkenes, three distinct processes have been identified which involve the alkene and two processes which are independent of alkene.A combination of product studies, rearrangements, dilution experiments and literature kinetic data allow the proposal of a unified mechanistic picture to describe these processes.Specifically, the role of α-H acidity of the carboxylyic acid component, electron deficient radical additions, metal complexed organic radicals, and the importance of an oxo-centered manganese(III) triangle are discussed as they relate to the lactone annulation reaction.Single electron transfer oxidation of alkenes is described as a route toward 1,2-diacetates of alkenes within the 8.1-7.5 eV I.P. range.Three less common modes of Mn(III) reaction are discussed and compared with the two primary processes of lactone annulation and 1,2-diacetate formation.
- Fristad, William E.,Peterson, John R.,Ernst, Andreas B.,Urbi, Gordon B.
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p. 3429 - 3442
(2007/10/02)
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- Manganese(III)-Mediated γ-Lactone Annulation
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The annulation of a γ-lactone ring onto an alkene by manganese(III) acetate oxidation of acetic acid was investigated.The regioselectivity of addition to unsymmetrically substituted alkenes is reported along with the stereoselectivity of addition to various acyclic and cyclic alkenes.Alkenes with ionization potentials above 8.2 eV were found to react in good yield.The role of acetic anhydride in these reactions was studied, and it was shown to be oxidized faster than acetic acid and also led to different products.The fate of oxidized acetic acid or anhydridein the absence of suitable acceptor molecule has also been quantitatively identified.The relationship of enolizability, or C-H acidity, of the carboxylic acid being oxidized was established quantitatively.
- Fristad, William E.,Peterson, John R.
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