932-16-1Relevant articles and documents
Photo-on-Demand Synthesis of Vilsmeier Reagents with Chloroform and Their Applications to One-Pot Organic Syntheses
Liang, Fengying,Eda, Kazuo,Okazoe, Takashi,Wada, Akihiro,Mori, Nobuaki,Konishi, Katsuhiko,Tsuda, Akihiko
, p. 6504 - 6517 (2021/05/06)
The Vilsmeier reagent (VR), first reported a century ago, is a versatile reagent in a variety of organic reactions. It is used extensively in formylation reactions. However, the synthesis of VR generally requires highly toxic and corrosive reagents such as POCl3, SOCl2, or COCl2. In this study, we found that VR is readily obtained from a CHCl3 solution containing N,N-dimethylformamide or N,N-dimethylacetamide upon photo-irradiation under O2 bubbling. The corresponding Vilsmeier reagents were obtained in high yields with the generation of gaseous HCl and CO2 as byproducts to allow their isolations as crystalline solid products amenable to analysis by X-ray crystallography. With the advantage of using CHCl3, which bifunctionally serves as a reactant and a solvent, this photo-on-demand VR synthesis is available for one-pot syntheses of aldehydes, acid chlorides, formates, ketones, esters, and amides.
Electronic Asymmetry of an Annelated Pyridyl-Mesoionic Carbene Scaffold: Application in Pd(II)-Catalyzed Wacker-Type Oxidation of Olefins
Bera, Jitendra K.,Dutta, Indranil,Kunnikuruvan, Sooraj,Reshi, Noor U Din,Saha, Sayantani,Yadav, Suman
, p. 11385 - 11393 (2020/11/23)
The two donor modules of an annelated pyridyl-mesoionic carbene ligand (aPmic) have different σ- and π-bonding characteristics leading to its electronic asymmetry. A Pd(II) complex 1 featuring aPmic catalyzes the oxidation of a wide range of terminal olefins to the corresponding methyl ketones in good to excellent yields in acetonitrile. The catalytic reaction is proposed to proceed via syn-peroxypalladation and a subsequent rate-limiting 1,2-hydride shift, which is supported by kinetic studies. The electronic asymmetry of aPmic renders a well-defined coordination sphere at Pd. The favored arrangement of reactants on the metal center features an olefin trans to the pyridyl module and a tbutylperoxide trans to the carbene. This arrangement gains added stability by the π-delocalization paved by the compatible orbitals on Pd, the pyridyl module, and the olefin that is perpendicular to the Pd(aPmic) plane. The π-interactions are absent in an alternate arrangement wherein the olefin is trans to the carbene. Density functional theory studies reveal the matching orbital overlaps responsible for the preferred arrangement over the other. This work provides an orbital description for the electronic asymmetry of aPmic.
Oxidative coupling of enolates using memory of chirality: An original enantioselective synthesis of quaternary α-amino acid derivatives
Mambrini, Antonin,Gori, Didier,Guillot, Régis,Kouklovsky, Cyrille,Alezra, Valérie
supporting information, p. 12742 - 12745 (2018/12/01)
We describe here the first enantioselective oxidative heterocoupling of enolates. Our strategy relies on the memory of chirality concept and allows the stereocontrolled formation of quaternary centres on α-amino acid derivatives with an enantiomeric excess of up to 94%.
Reactions of nitrilium salts with indole and pyrrole and their derivatives in the synthesis of imines, ketones and secondary amines
Giles, Robert G.,Heaney, Harry,Plater, M. John
, p. 7367 - 7385 (2015/08/24)
Abstract Reactions of N-methyl- and N-ethyl-nitrilium salts with indole and pyrrole and their derivatives yield imines or imine salts in good yields. The related imines are obtained from the salts after careful basification and hydrolysis of the imine salts or the imines by heating with aqueous base give the related ketones in good yields. Alternatively, the imine salts can be reduced using sodium borohydride in methanol to give the related secondary amines.
Access to indoles via Diels-Alder reactions of 5-methylthio-2-vinylpyrroles with maleimides
Noland, Wayland E.,Lanzatella, Nicholas P.,Dickson, Rozalin R.,Messner, Mary E.,Nguyen, Huy H.
, p. 795 - 808 (2013/08/23)
Diels-Alder reactions of 5-methylthio-2-vinyl-1H-pyrroles with maleimides followed by isomerization gave tetrahydroindoles in moderate to good yield. Aromatization using activated MnO2 in refluxing toluene gave the corresponding 2-methylthioindoles in good yields, and demethylthioation using Raney nickel gave the 2-H indoles in excellent yields. The protection of the adducts produced aromatization in improved yield, demonstrating the effectiveness of the methylthio group as a protecting group for pyrroles; however, 5-methylthio-2-vinylpyrrole was shown to perform with slightly less efficiency than 2-vinylpyrrole in Diels-Alder reactions, indicating the protective group was more deactivating than desired. This route toward indoles offers high convergency and conveniently available starting materials that are easily purified. Bis-methylthioated vinylpyrroles were shown to have potential as highly activated Diels-Alder dienes.
Green N-methylation of electron deficient pyrroles with dimethylcarbonate
Laurila, Michael L.,Magnus, Nicholas A.,Staszak, Michael A.
experimental part, p. 1199 - 1201 (2010/04/22)
The N-methylation of electron-deficient pyrroles was affected using dimethyl carbonate in the presence of DMF and catalytic DABCO. This alkylation methodology has proven useful for the alkylation of a variety of pyrroles in 72-98% yields and is considered to be green chemistry relative to the more common use of methyl halides or dimethyl sulfate.
Unexpectedly high activity of Zn(OTf)2·6H2O in catalytic Friedel-Crafts acylation reaction
He, Fei,Wu, Huayue,Chen, Jiuxi,Su, Weike
, p. 255 - 264 (2008/03/17)
Zn(OTf)2·6H2O was used to promote Friedel-Crafts acylation of aromatics. The work describes the high activity and efficiency of Zn(OTf)2·6H2O in acylation of aromatics, and the catalyst has surpassed most metal triflates in dispensing when dried at high temperature under vacuum before use. Copyright Taylor & Francis Group, LLC.
Ytterbium (III) trifluoromethanesulfonate catalysed Friedel-Crafts acylation of 1-methylpyrrole in ionic liquid
Su, Weike,Wu, Chunlei,Su, Hao
, p. 67 - 68 (2007/10/03)
In the presence of a catalytic amount of ytterbium (III) trifluoromethanesulfonate [Yb(OTf)3], 1-methylpyrrole can easily react with acyl chlorides in an ionic liquid [bpy][BF4](bpy=1- butylpyridine) to form corresponding ketones in satisfactory yield. The recyclability of the ionic liquid/catalyst system is demonstrated.
Vilsmeier-Haack preparation of 2-acylpyrroles using bis(trichloromethyl) carbonate and N,N-dimethylacylamines
Shi,Su,Shan
, p. 1019 - 1021 (2007/10/03)
A series of 2-acylpyrroles were synthesized by using bis(trichloromethyl) carbonate and N,N-dimethylacylamines as Vilsmeier-Haack reagents under mild conditions in good yields.
Synthesis of 4- and 6-substituted nitroindoles
Moskalev, Nikolai,Barbasiewicz, Micha?,Ma?kosza, Mieczys?aw
, p. 347 - 358 (2007/10/03)
Enolizable ketones react with m-nitroaniline in the presence of strong base such as t-BuOK to give 4- and 6-substituted nitroindoles. The reaction proceeds via oxidative nucleophilic substitution of hydrogen in m-nitroaniline with enolate anions in positions ortho to the amino group giving anionic σH adducts that are additionally stabilized by intramolecular interaction between the amino and the carbonyl group. Spontaneous oxidation of the σH adducts followed by the Bayer type condensation of the produced ortho-aminonitrobenzyl ketones gives 4- and 6-substituted nitroindoles. The scope of this reaction and its basic mechanistic features are discussed.
