- Nickel-Catalyzed Addition of Aryl Bromides to Aldehydes to Form Hindered Secondary Alcohols
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Transition-metal-catalyzed addition of aryl halides across carbonyls remains poorly developed, especially for aliphatic aldehydes and hindered substrate combinations. We report here that simple nickel complexes of bipyridine and PyBox can catalyze the addition of aryl halides to both aromatic and aliphatic aldehydes using zinc metal as the reducing agent. This convenient approach tolerates acidic functional groups that are not compatible with Grignard reactions, yet sterically hindered substrates still couple in high yield (33 examples, 70% average yield). Mechanistic studies show that an arylnickel, and not an arylzinc, adds efficiently to cyclohexanecarboxaldehyde, but only in the presence of a Lewis acid co-catalyst (ZnBr2).
- Garcia, Kevin J.,Gilbert, Michael M.,Weix, Daniel J.
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supporting information
p. 1823 - 1827
(2019/02/14)
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- Iron-catalyzed oxidative biaryl cross-couplings via mixed diaryl titanates: Significant influence of the order of combining aryl Grignard reagents with titanate
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The mixed diaryl titanates were used for the first time to modify the reactivity of two aryl Grignard reagents. Two titanate intermediates, Ar[Ar′Ti(OR)3]MgX and Ar′[ArTi(OR)3]MgX, formed via alternating the sequence of combining Grignard reagents with ClTi(OR)3 showed a significant reactivity difference. Taking advantage of such different reactivity, two highly structurally similar aryl groups could be facilely assembled through iron-catalyzed oxidative cross-couplings using oxygen as the oxidant. This journal is
- Liu, Kun Ming,Wei, Juan,Duan, Xin Fang
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supporting information
p. 4656 - 4658
(2015/05/27)
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- Rapid and efficient copper-catalyzed finkelstein reaction of (hetero)aromatics under continuous-flow conditions
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A general, rapid, and efficient method for the copper-catalyzed Finkelstein reaction of (hetero)aromatics has been developed using continuous flow to generate a variety of aryl iodides. The described method can tolerate a broad spectrum of functional groups, including N-H and O-H groups. Additionally, in lieu of isolation, the aryl iodide solutions were used in two distinct multistep continuous-flow processes (amidation and Mg-I exchange/nucleophilic addition) to demonstrate the flexibility of this method.
- Chen, Mao,Ichikawa, Saki,Buchwald, Stephen L.
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supporting information
p. 263 - 266
(2015/02/05)
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- Air-stable solid aryl and heteroaryl organozinc pivalates: Syntheses and applications in organic synthesis
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A wide range of air-stable, solid, polyfunctional aryl and heteroarylzinc pivalates were efficiently prepared by either magnesium insertion or Hal/Mg exchange followed by transmetalation with Zn(OPiv)2 (OPiv=pivalate). By reducing the amount of
- Manolikakes, Sophia M.,Ellwart, Mario,Stathakis, Christos I.,Knochel, Paul
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supporting information
p. 12289 - 12297
(2015/03/31)
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- A flow microreactor system enables organolithium reactions without protecting alkoxycarbonyl groups
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A flow microreactor system consisting of micromixers and microtube reactors provides an effective tool for the generation and reactions of aryllithiums bearing an alkoxycarbonyl group at para-, meta-, and ortho-positions. Alkyl p- and m-lithiobenzoates were generated by the I/Li exchange reaction with PhLi. The Br/Li exchange reactions with sBuLi were unsuccessful. Subsequent reactions of the resulting aryllithiums with electrophiles gave the desired products in good yields. On the other hand, alkyl o-lithiobenzoates were successfully generated by the Br/ Li exchange reaction with sBuLi. Subsequent reactions with electrophiles gave the desired products in good yields.
- Nagaki, Aiichiro,Kim, Heejin,Moriwaki, Yuya,Matsuo, Chika,Yoshida, Jun-Ichi
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supporting information; experimental part
p. 11167 - 11177
(2010/11/04)
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- Phosphazene base-promoted halogen-zinc exchange reaction of aryl iodides using diethylzinc
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The use of catalytic t-Bu-P4 base dramatically improved the performance of halogen-zinc exchange of aryl iodides, and the arylzinc derivatives were functionalized under copper-free reaction conditions. The Royal Society of Chemistry 2006.
- Ueno, Masahiro,Wheatley, Andrew E. H.,Kondo, Yoshinori
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p. 3549 - 3550
(2008/09/19)
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- Method for producing Grignard compounds
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The invention relates to a process for preparing Grignard compounds of the formula I. The invention additionally relates to compounds of the formula I and to polymer-bound compounds of the formula Ia. The invention further relates to the use of the process for preparing substance libraries and to the use of the compounds of the formulae I and Ia in chemical synthesis.
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Page/Page column 10
(2008/06/13)
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- Preparation of highly functionalized Grignard reagents by an iodine-magnesium exchange reaction and its application in solid-phase synthesis
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At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.
- Boymond, Laure,Rottlaender, Mario,Cahiez, Gerard,Knochel, Paul
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p. 1701 - 1703
(2007/10/03)
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- Nozaki-Hiyama-Kishi reactions catalytic in chromium
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A procedure is described which allows for the first time to perform chromium-catalyzed additions of organic halides to aldehydes ("Nozaki-Hiyama-Kishi reactions"). The reactions are mediated by trimethylchlorosilane, and the active Cr2+ species is constantly recycled by means of nontoxic, commercial manganese powder as the stoichiometric reductant. This method nicely applies to different substituted aryl, heteroaryl, alkynyl, alkenyl, and allyl halides as well as to alkenyl inflates as the starting materials and rivals its stoichiometric precedent in terms of efficiency, practicability, and chemo- and diastereoselectivity. Specifically, it has been demonstrated that the addition of crotyl bromide to various aldehydes is highly stereoconvergent, i.e. the respective anti-configurated homoallyl alcohols are obtained with excellent diastereomeric excess independent of whether the starting halide is (E)- or (Z)-configurated. In accordance with the likely catalytic cycle, both CrCl2(cat.) or CrCl3(cat) turned out to efficiently mediate reactions of this type, with the latter being preferred for practical reasons. Finally, attempts were made to optimize the number of turnovers in chromium. In this context the use of either chromocene (Cp2Cr) or CpCrCl2·THF as "pre-catalysts" were found to significantly upgrade the efficiency of such C-C bond formations, with ≤ 1 mol % of chromium being required in these cases for quantitative conversions.
- Fürstner, Alois,Shi, Nongyuan
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p. 12349 - 12357
(2007/10/03)
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- Halogen-Zinc Exchange Reaction of Haloaromatics with Lithium Trimethylzincate
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Lithium aryldimethylzincates were prepared using a halogen-zinc exchange reaction of aromatic halides with lithium trialkylzincates, and the reactions with some electrophiles for the functionalization of aromatic rings were investigated.
- Kondo, Yoshinori,Takazawa, Nobuo,Yamazaki, Chizuru,Sakamoto, Takao
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p. 4717 - 4718
(2007/10/02)
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