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《化学:亚洲杂志》2017,12(24):3123-3127
The utility of benziodoxole triflate, derived from α,α‐bis(trifluoromethyl)‐2‐iodobenzyl alcohol, as a versatile reagent for iodo(III)cyclization via electrophilic activation of alkyne, is reported herein. The reagent promotes cyclization of alkynes tethered to a variety of nucleophilic moieties, affording benziodoxole‐appended (hetero)arenes such as benzofurans, benzothiophenes, isocoumarins, indoles, and polyaromatics under mild conditions. This unprecedented class of (hetero)aryl‐IIII compounds proved easy to purify, stable, and amenable to various synthetic transformations. 相似文献
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Hypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non‐racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations. 相似文献
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A regioselective fluorocyclisation of β,γ-unsaturated oximes through I(I)/I(III) catalysis is disclosed to generate 5-fluoromethylated isoxazolines. The transformation leverages p-iodotoluene as an inexpensive catalyst, Selectfluor® as the terminal oxidant and an amine⋅HF complex (1 : 7.5) as both the fluoride and Brønsted acid source. The λ3-iodane p-TolIF2, which is generated in situ, engages the pendant alkene of the substrate to facilitate a cyclisation/fluorination sequence. A range of 5-fluoromethyl isoxazolines can be generated using this method, including aliphatic and aromatic systems (up to 56 % yield). Single crystal X-ray analysis of a representative example reveals a conformation that is consistent with the stereoelectronic gauche effect between the exocyclic C(sp3)−F bond and the C(sp3)−O of the isoxazoline (ϕOCCF=−62.0°). 相似文献
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Copper‐Catalyzed Oxy‐Alkenylation of Homoallylic Alcohols to Generate Functional syn‐1,3‐Diol Derivatives 下载免费PDF全文
Dean Holt Prof. Matthew J. Gaunt 《Angewandte Chemie (International ed. in English)》2015,54(27):7857-7861
A novel method for the synthesis of a wide range of functionalized 1,3‐diol derivatives is reported. Employing a copper‐catalyzed oxy‐alkenylation strategy, a range of readily available, substituted homoallylic alcohol derivatives and alkenyl(aryl) iodonium salts combine to form syn‐1,3‐carbonates in excellent yield and with high selectivity. Furthermore, the products formed are amenable to an iterative reaction sequence, thus affording highly complex polyketide‐like fragments. 相似文献
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Dual Hypervalent Iodine(III) Reagents and Photoredox Catalysis Enable Decarboxylative Ynonylation under Mild Conditions 下载免费PDF全文
Hanchu Huang Guojin Zhang Prof. Dr. Yiyun Chen 《Angewandte Chemie (International ed. in English)》2015,54(27):7872-7876
A combination of hypervalent iodine(III) reagents (HIR) and photoredox catalysis with visible light has enabled chemoselective decarboxylative ynonylation to construct ynones, ynamides, and ynoates. This ynonylation occurs effectively under mild reaction conditions at room temperature and on substrates with various sensitive and reactive functional groups. The reaction represents the first HIR/photoredox dual catalysis to form acyl radicals from α‐ketoacids, followed by an unprecedented acyl radical addition to HIR‐bound alkynes. Its efficient construction of an mGlu5 receptor inhibitor under neutral aqueous conditions suggests future visible‐light‐induced biological applications. 相似文献
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Gerhard Sorg Anne Mengel Günther Jung Jrg Rademann 《Angewandte Chemie (International ed. in English)》2001,40(23):4395-4397
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Liam T. Ball Prof. Dr. Guy C. Lloyd‐Jones Dr. Christopher A. Russell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(10):2931-2937
1‐Hydroxy‐1,2‐benziodoxol‐3(1H)‐one (IBA) is an efficient terminal oxidant for gold‐catalysed, three‐component oxyarylation reactions. The use of this iodine(III) reagent expands the scope of oxyarylation to include styrenes and gem‐disubstituted olefins, substrates that are incompatible with the previously reported Selectfluor‐based methodology. Diverse arylsilane coupling partners can be employed, and in benzotrifluoride, homocoupling is substantially reduced. In addition, the IBA‐derived co‐products can be recovered and recycled. 相似文献
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Hypervalent‐Iodine(III)‐Mediated Oxidative Methodology for the Synthesis of Fused Triazoles 下载免费PDF全文
The organic chemistry of hypervalent organoiodine compounds has been an area of unprecedented development. This surge in interest in the use of hypervalent iodine compounds has mainly been owing to their highly selective oxidizing properties, environmentally benign character and commercial availability. Hypervalent iodine reagents have also been used as an alternative to toxic heavy metals, owing to their low toxicity and ease of handling. Hypervalent organoiodine(III) reagents are versatile oxidants that have been successfully employed to extend the scope of selective oxidative transformations of complex organic molecules in synthetic chemistry. This Focus Review concerns the tandem in situ generation and 1,5‐electrocyclization of N‐heteroaryl nitrilimines into fused triazoles. We describe the importance of recently developed hypervalent‐organoiodine(III)‐catalyzed oxidative cyclization reactions, building towards the conclusion that hypervalent iodine chemistry is a promising frontier for oxidative cyclization, in particular of hydrazones, for the synthesis of fused triazoles. 相似文献
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On the Formation of Intermetalloid Clusters: Titanocene(III)diammin as a Versatile Reactant Toward Nonastannide Zintl Clusters 下载免费PDF全文
Dr. Christian B. Benda Dr. Markus Waibel Prof. Dr. Thomas F. Fässler 《Angewandte Chemie (International ed. in English)》2015,54(2):522-526
The reactivity of TiCp2Cl2 (d0) towards Zintl clusters was studied in liquid ammonia (Cp=cyclopentadienyl). Reduction of TiIVCp2Cl2 and ligand exchange led to the formation of [TiIIICp2(NH3)2]+, also obtainable by recrystallization of [CpTiIIICl]2. Upon reaction with [K4Sn9], ligand exchange leads to [TiCp2(η1‐Sn9)(NH3)]3?. A small variation of the stoichiometry led to the formation of [Ti(η4‐Sn8)Cp]3?, which cocrystallizes with [TiCp2(NH3)2]+ and [TiCp2(η1‐Sn9)(NH3)]3?. Finally, the large intermetalloid cluster anion [Ti4Sn15Cp5]n? (n=4 or 5) was obtained from the reaction of K12Sn17 and TiCp2Cl2 in liquid ammonia. The isolation of three side products, [K([18]crown‐6)]Cp, [K([18]crown‐6)]Cp(NH3), and [K([2.2]crypt)]Cp, suggests a stepwise elimination of the Cl? and Cp? ligands from TiCp2Cl2 and thus gives a hint to the mechanism of the product formation in which [Ti(η4+2‐Sn8)Cp]3? has a key role. 相似文献
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Laura Fra Prof. Dr. Kilian Muñiz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4351-4354
An intramolecular approach towards the regioselective construction of 2,3‐diarylated indoles is reported. The reaction follows an intramolecular electrophilic N?H and C?H bond functionalization between the aniline and acetylene. This methodology employs the concept of a traceless tether to provide access to the free 2,3‐diarylated indole products comprising a total of 18 examples. Hypervalent iodine reagents were identified as suitable promoters and four different protocols are provided, including stoichiometric and catalytic transformations. 相似文献
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The reaction between thallium(I) and [CoIIIW12O40]5- in the presence of ruthenium(III) as catalyst proceeds viainitial outer-sphere oxidation of the catalyst to ruthenium(VI). The ruthenium(IV) thus generated will oxidize thallium(I)
to an unstable thallium(II) which by reacting with oxidant gives the final product, thallium(III). The formation of ruthenium(II)
by direct two-electron reduction of the catalyst by thallium(I) is thermodynamically less favorable. The reaction rate is
unaffected by the [ H+ ], whereas it is catalyzed by chloride ion . The formation of reactive chlorocomplex,TlCl, in a prior equilibrium is the
reason for the chloride ion catalysis. Increasing the relative permittivity of the medium increases the rate of the reaction,
which is attributed to the formation of an outer-sphere complex between the catalyst and oxidant.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Advances in Iodine(III)‐Mediated Halogenations: A Versatile Tool to Explore New Reactivities and Selectivities 下载免费PDF全文
Andreas M. Arnold Anna Ulmer Dr. Tanja Gulder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(26):8728-8739
Within the repertoire of organic chemical transformations, the halogenation of substrates is among the most versatile, reliable, and broadly applicable reactions. Although a multitude of different methods are known today, there is still a huge demand for novel and, in particular, catalytic halogenation methods that exhibit new reactivities and selectivities. The class of hypervalent iodanes meets exactly these needs and thus offers a great opportunity to fuel this highly desirable direction within the field of halogenation chemistry. This Concept gives a short overview of recent examples focusing on selective and/or mechanistically unusual halogenations. 相似文献