- Denitrogenative Hydrotrifluoromethylation of Benzaldehyde Hydrazones: Synthesis of (2,2,2-Trifluoroethyl)arenes
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Reacting hydrazones of arylaldehydes with Togni's CF3-benziodoxolone reagent, in the presence of potassium hydroxide and cesium fluoride, induces a denitrogenative hydrotrifluoromethylation event to produce (2,2,2-trifluoroethyl)arenes. This novel reaction was tolerant to many electronically-diverse functional groups and substitution patterns, as well as naphthyl- and heteroaryl-derived substrates. Advantages of this process include the easy access to hydrazone precursors on a large scale, speed and operational simplicity, and being transition metal-free.
- Zhao, Zhensheng,Ma, Kevin C. Y.,Legault, Claude Y.,Murphy, Graham K.
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supporting information
p. 11240 - 11245
(2019/08/20)
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- Metal-Free Construction of the C(sp3)-CF3 Bond: Trifluoromethylation of Hydrazones with Togni's Reagent under Mild Conditions
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A metal-free trifluoromethylation of hydrazones with Togni's reagent under mild conditions was developed. Various functional groups including ester, methoxy, dimethoxy, nitro, halogen, and heterocyclic compounds were tolerated. This simple and green strategy provides a practical tool to construct C(sp3)-CF3 bonds.
- Zeng, Huiying,Luo, Zhen,Han, Xinlong,Li, Chao-Jun
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supporting information
p. 5948 - 5951
(2019/08/29)
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- Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
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Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
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supporting information
p. 16520 - 16524
(2018/11/23)
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- Synthesis of Aryldihalomethanes by Denitrogenative Dihalogenation of Benzaldehyde Hydrazones
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We report a denitrogenative dihalogenation reaction of phenyldiazomethanes in which the hypervalent iodine reagents PhICl2 and TolIF2 act as surrogates for elemental chlorine and fluorine. Halogen transfer from iodane to aryldiazomethane is described, as is a tandem oxidative dihalogenation reaction between iodane and hydrazone. This is the first use of non-α-stabilized diazo compounds in this reaction, which provided an efficient synthesis of aryldifluoromethane (ArCHF2) and aryldichloromethane (ArCHCl2) derivatives. (Figure presented.).
- Zhao, Zhensheng,Kulkarni, Kaivalya G.,Murphy, Graham K.
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supporting information
p. 2222 - 2228
(2017/07/07)
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- Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds
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Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.
- Wang, Haining,Dai, Xi-Jie,Li, Chao-Jun
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p. 374 - 378
(2017/04/03)
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- Denitrogenative hydrofluorination of aromatic aldehyde hydrazones using (difluoroiodo)toluene
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An operationally simple conversion of aromatic aldehyde hydrazones to monofluoromethylated arenes is reported. The hypervalent iodine reagent TolIF2 serves as an oxidant, converting the hydrazone to the corresponding diazo compounds. The by-product of the oxidation process, HF, is consumed in situ by a denitrogenative hydrofluorination reaction of the diazo group.
- Kulkarni, Kaivalya G.,Miokovic, Boris,Sauder, Matthew,Murphy, Graham K.
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supporting information
p. 9907 - 9911
(2016/10/31)
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- Synthesis of esters by in situ formation and trapping of diazoalkanes
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A general method has been developed for the in situ formation and trapping of diazoalkanes by carboxylic acids to form esters. The method is applicable to a large variety of carboxylic acids using diazo compounds that are formed from the hydrazones of benzaldehydes and aryl ketones. In situ reaction monitoring with IR spectroscopy (ReactIR) was used to demonstrate that slow addition of the hydrazone to a mixture of oxidant and carboxylic acid avoids the buildup of the diazo compound. This method enables the safe preparation of esters from simple precursors without isolation of diazo compounds.
- Squitieri, Richard A.,Shearn-Nance, Galen P.,Hein, Jason E.,Shaw, Jared T.
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p. 5278 - 5284
(2016/07/14)
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- A Versatile Room-Temperature Route to Di- and Trisubstituted Allenes Using Flow-Generated Diazo Compounds
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A copper-catalyzed coupling reaction between flow-generated unstabilized diazo compounds and terminal alkynes provides di- and trisubstituted allenes. This extremely mild and rapid transformation is highly tolerant of several functional groups. Well tolerated: A mild copper-catalyzed coupling reaction between unstabilized diazo compounds (generated in flow) and terminal alkynes is reported. The method provides di- and trisubstituted allenes with high functional-group tolerance.
- Poh, Jian-Siang,Tran, Duc N.,Battilocchio, Claudio,Hawkins, Joel M.,Ley, Steven V.
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supporting information
p. 7920 - 7923
(2015/06/30)
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- Facile synthesis of (E)-β-(trifluoromethyl)styrenes from halothane (HCFC-123B1)
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A practical and convenient synthesis of (E)-β-(trifluoromethyl)styrenes has been achieved by the reaction of commercially available halothane (HCFC-123B1) and hydrazones prepared in advance in situ, in the presence of 1,2-ethylenediamine and a catalytic amount of CuCl2·2H2O at room temperature. The products showed acceptable to high yields and high to excellent stereoselectivity. This handy synthetic method provided easy access to a variety of (E)-β-(trifluoromethyl)styrenes.
- Hirotaki, Kensuke,Kawazoe, Genyu,Hanamoto, Takeshi
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p. 169 - 173
(2015/03/04)
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- Solid-state intermolecular contacts involving the nitrile group in p-cyano-N-(p-cyanobenzylidene)aniline and 4,4′-(azinodimethylidyne)bis- benzonitrile
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As part of an investigation of the solid-state intermolecular contacts in which the nitrile group participates, the crystal structures of p-cyano-N-(p-cyanobenzylideneaniline), C15H9N3 (CN/CN) and 4,4′-(azinodimethylidyne)
- Ojala, Charles R.,Ojala, William H.,Britton, Doyle
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experimental part
p. 464 - 469
(2011/12/22)
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- 4-(4-Chloro-benzyl-idene-hydrazono-methyl)-benzonitrile and the bromo and iodo analogs
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4-Cyano-4′-chlorobenzalazine [systematic name: 4-(4-chloro-benzyl- idenehydrazonomethyl)benzonitrile], C15-H10ClN 3, oc-curs in two polymorphs. Polymorph A is iso-struct-ural with the corresponding dichloro compound. Polym
- Ojala, Charles R.,Ojala, William H.,Britton, Doyle
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- A novel approach to fluoro-containing alkenes
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A new and general one-pot transformation of aromatic aldehydes to fluorinated olefins containing -CH=C(Cl)CF3 or -CH=C(F)CClF2 moieties is described. Freons CCl3CF3 and CCl2FCClF2 were used as trifluoromethyl and difluoromethyl C2-building blocks respectively. A proposed mechanism for the reaction is discussed.
- Korotchenko, Vasily N,Shastin, Alexey V,Nenajdenko, Valentine G,Balenkova, Elisabeth S
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p. 7519 - 7527
(2007/10/03)
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- A novel synthetic approach to dichlorostyrenes
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We found that N-unsubstituted hydrazones of aromatic aldehydes can be easily converted to the corresponding 1,1-dichlorostyrenes in the reaction with carbon tetrachloride using copper (I) chloride as catalyst. Factors affecting the route of the reaction and yields of the products were investigated. A proposed mechanism for the reaction is discussed. (C) 2000 Published by Elsevier Science Ltd.
- Shastin,Korotchenko,Nenajdenko,Balenkova
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p. 6557 - 6563
(2007/10/03)
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- Synthesis, characterisation, and phase behaviour of some azines with potential optical nonlinearities of second order
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Some azines with potential nonlinear optical properties of the second order have been synthesised by condensation of the appropriate hydrazones and aldehydes. The compounds have been chemically functionalised to allow their use in the synthesis of polymers containing the azine groups as side chain pendants. The characterisation of the phase behaviour, performed by DSC, X-ray diffraction and polarising microscopy methods, shows that most of the compounds exhibit enantiotropic liquid crystalline properties. Some peculiar features concerning solid state polymorphism have also been investigated.
- Centore,Panunzi,Roviello,Sirigu,Villano
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p. 107 - 120
(2007/10/03)
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