- Reaction of the C60 radical anion with alkyl halides
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The reaction of the C60 radical anion (C60-) with α-bromo-1,3-dicarbonyl compounds selectively afforded the methanofullerene derivatives. The reaction with benzyl halide and 1,2-bis(dihalomethyl)benzene afforded the corresponding 1,4-dibenzylated C60 derivative and cycloaddition product, respectively. The possible mechanisms for the formation of the fullerene adducts are proposed.
- Maeda, Yutaka,Sanno, Makoto,Morishita, Tatsunari,Sakamoto, Kodai,Sugiyama, Eiichiro,Akita, Saeka,Yamada, Michio,Suzuki, Mitsuaki
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Read Online
- Palladium-catalyzed distannylation of ortho-quinodimethanes
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An exo-diene moiety of various ortho-quinodimethanes, regardless of its transient character, was inserted into a Sn-Sn σ-bond of hexabutyldistannane in the presence of a palladium catalyst, giving α,α′-bis(tributylstannyl)-o-xylenes straightforwardly.
- Yoshida, Hiroto,Nakano, Saori,Yamaryo, Yasuhito,Ohshita, Joji,Kunai, Atsutaka
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Read Online
- A Unified Catalytic Asymmetric (4+1) and (5+1) Annulation Strategy to Access Chiral Spirooxindole-Fused Oxacycles
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A unified catalytic asymmetric (N+1) (N=4, 5) annulation reaction of oxindoles with bifunctional peroxides has been achieved in the presence of a chiral phase-transfer catalyst (PTC). This general strategy utilizes peroxides as unique bielectrophilic four- or five-atom synthons to participate in the C?C and the subsequent umpolung C?O bond-forming reactions with one-carbon unit nucleophiles, thus providing a distinct method to access the valuable chiral spirooxindole-tetrahydrofurans and -tetrahydropyrans with good yields and high enantioselectivities under mild conditions. DFT calculations were performed to rationalize the origin of high enantioselectivity. The gram-scale syntheses and synthetic utility of the resultant products were also demonstrated.
- Gao, Min,Gong, Xiangnan,Hu, Lin,Luo, Yanshu,Xia, Yuanzhi,Xu, Qianlan,Zhao, Yukun
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p. 19813 - 19820
(2021/08/03)
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- Chemo- and Enantioselective Oxidative α-Azidation of Carbonyl Compounds
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We report high-performance I+/H2O2 catalysis for the oxidative or decarboxylative oxidative α-azidation of carbonyl compounds by using sodium azide under biphasic neutral phase-transfer conditions. To induce higher reactivity especially for the α-azidation of 1,3-dicarbonyl compounds, we designed a structurally compact isoindoline-derived quaternary ammonium iodide catalyst bearing electron-withdrawing groups. The nonproductive decomposition pathways of I+/H2O2 catalysis could be suppressed by the use of a catalytic amount of a radical-trapping agent. This oxidative coupling tolerates a variety of functional groups and could be readily applied to the late-stage α-azidation of structurally diverse complex molecules. Moreover, we achieved the enantioselective α-azidation of 1,3-dicarbonyl compounds as the first successful example of enantioselective intermolecular oxidative coupling with a chiral hypoiodite catalyst.
- Hattori, Yuhei,Ishihara, Kazuaki,Sahara, Naoto,Tsukahara, Mayuko,Uyanik, Muhammet
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supporting information
p. 17110 - 17117
(2020/08/10)
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- 2,6-Diazasemibullvalenes: Synthesis, structural characterization, reaction chemistry, and theoretical analysis
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A series of 2,6-diazasemibullvalenes (NSBVs) were synthesized and isolated from the reaction of 1,4-dilithio-1,3-dienes with nitriles via oxidant-induced C-N bond formation. For the first time, the activation barrier and an X-ray crystal structure of a su
- Zhang, Shaoguang,Wei, Junnian,Zhan, Ming,Luo, Qian,Wang, Chao,Zhang, Wen-Xiong,Xi, Zhenfeng
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supporting information; scheme or table
p. 11964 - 11967
(2012/09/08)
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- Synthesis of new bis-BINOL-2,2′-ethers and bis-H8BINOL-2,2′-ethers evaluation of their Titanium complexes in the asymmetric ethylation of benzaldehyde
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The preparation by means of different synthetic paths of a series of bis-BINOL and bis-H8BINOL ligands is described. The ligands consist of two BINOL or H8BINOL fragments, joined by diverse linkages through the oxygen at the 2′-position of the arylic fragments. These ligands were applied to the Ti(OiPr)4 catalyzed asymmetric alkylation of benzaldehyde with Et2Zn. The performance of these catalysts is very sensitive to the nature of the ether linkage. The ligand with a propylene link shows better enantioselectivity (ca. 70%) than those with two or four carbon atoms joining the BINOL fragments. Furthermore, using the propylene link, but replacing (R)-BINOL by (R)-H8BINOL, a significant improvement in the stereoselectivity of the catalysts was achieved (ca. 80% ee in (R)-1-phenylpropan-1-ol). A cooperative effect was observed between the chirality at the BINOL fragment and that of a (S,S)-4,5-bis(methylene)-2,2-dimethyl-1,3-dioxolane link, derived from tartaric acid. When this chiral link combines with two (S)-BINOL fragments, the alkylation of benzaldehyde in toluene produces 70% ee of (S)-1-phenylpropan-1-ol, while the (R)-BINOL derivative ligand with the same link, in identical conditions, yields only 40% ee of the (R)-alcohol.
- Abreu, Artur R.,Pereira, Mariette M.,Bayón, J. Carles
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experimental part
p. 743 - 749
(2010/09/14)
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- Homologation method for preparation of substituted pentacenes and naphthacenes
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Multi-substituted pentacenes, such as 1,2,3,4,6,8,9,10,11,13- decasubstituted pentacenes (Type I), 1,2,3,4,6,-13-hexasubstituted pentacenes (Type II), 1,2,3,4-tetrasubstituted pentacenes (Type III), and 2,3-disubstituted pentacenes (Type IV), 1,2,3,4,6,11
- Takahashi, Tamotsu,Li, Shi,Huang, Wenying,Kong, Fanzhi,Nakajima, Kiyohiko,Shen, Baojian,Ohe, Takahiro,Kanno, Ken-Ichiro
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p. 7967 - 7977
(2007/10/03)
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- An expedient and highly selective iodination of alcohols using a KI/BF3·Et2O system
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Alkyl iodides are prepared in high yields by treatment of allylic and benzylic alcohols with an equimolar amount of KI in the presence of BF3·Et2O in dioxane under mild conditions.
- Bandgar,Sadavarte,Uppalla
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p. 951 - 953
(2007/10/03)
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- The Transformation of Cyclic Alcohols into Cyclic Acetals through a New Oxygen Atom Insertion by Photolysis in the Presence of Lead Tetraacetate and Iodine
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Photolysis of the hypoiodites of steroidal cyclic homoallyl alcohols such as cholesterol and of cyclic alcohols such as 5α-androstan-17β-ol generated in situ in bnezene with three molar equivalents each of lead tetraacetate and iodine was found generally to result in the unprecedented formation of corresponding lactol acetates in yields up to 66percent.The lactol acetates are readily hydrolysed to lactols in most cases during their isolation and lactols are isolated products.Thus, cholesterol gave 4-oxa-A-homocholest-5-en-3-ol and its acetate in a 53percent yield.The products differ considerably from those reported by us after the photolysis of the hypoiodites by using mercury(II) oxide and iodine as the reagents for generating the hypoiodites; they also differ from those in the oxidation of the steroidal alcohols with lead tetraacetate alone.The photolysis of the hypoiodite of 2,2-dimethyl-5β-cholestan-3-ol was found to lead to the formation of an anomaluos lactol, 2α-iodomethyl-2β-methyl-4-oxa-A-homo-5α-cholestan-4ξ-ol together with normal lactol.We discuss the paths of the formation of the lactol acetates involving β-scission of the alkoxyl radicals.A new process was found in the photolysis of 2-indanol hypoiodite in the presence of lead tetraacetate and iodine.Our previously suggested pathways to the formation of 3α,5-epoxy-6-iodo-4-oxa-A-homo-5α-cholestanes and 3-formyloxy-2-iodo-2,30seco-A-norcholest-5-ene in the photolysis of cholesterol hypoiodite in the presence of mercury(II) oxide and iodine were supported by the results of the photolysis of 4-oxa-A-homocholest-5-en-3-ol hypoiodite in the presence of mercury(II) oxide and iodine were supported by the results of the photolysis of 4-oxa-A-homocholest-5-en-3-ol hypoiodite in the presence of mercury(II) oxide and iodine.
- Suginome, Hiroshi,Washiyama, Haruka,Yamada, Shinji
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p. 1071 - 1084
(2007/10/02)
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- δ-Hydrogen Abstraction from Alkyl and Phosphine Ligands Co-ordinated to Platinum(II); Formation of Benzoplatinacyclopentene Complexes
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Reactions of (cod = cyclo-octa-1,5-diene) with Mg(CH2C6H4Me-o)Br and tertiary phosphines (PR3) afford cis- (R = Et or Ph), which on refluxing in xylene give the benzoplatinacyclopentene complexes via δ-hydrogen abstraction reactions.Using PPh2(C6H4Me-o), metallation of the phosphine is preferred and the first obtained product after refluxing in xylene is >.On further refluxing in xylene, this compound again eliminates o-xylene to give the known .Using P(C6H4Me-o)3, the bulkiness of the phosphine makes alkylation unfavourable and the fluxional Br> is obtained.The variable-temperature n.m.r. spectra of this compound are interpreted in terms of hindered rotation around the Pt-P and P-C bonds giving rise to two different conformers at low temperature, each with all methyl groups non-equivalent.The compounds have been identified by their spectroscopic properties and some of their reaction chemistry is discussed.
- Chappell, S. David,Cole-Hamilton, David J.
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p. 1051 - 1058
(2007/10/02)
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