- Regioselective Synthesis of Acylated N-Heterocycles via the Cascade Reactions of Saturated Cyclic Amines with 2-Oxo-2-arylacetic Acids
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A highly regioselective and versatile synthesis of acylated N-heterocycles from the cascade reactions of saturated cyclic amines with 2-oxo-2-arylacetic acids is presented. Mechanistically, the formation of the title compounds involves first a C(sp3)-H bond dehydrogenation of cyclic amine to give an enamine intermediate followed by its cross coupling with the acyl species in situ generated through the decarboxylation of 2-oxo-2-arylacetic acid. Interestingly, in this cascade process, the copper catalyst is believed to play a crucial role not only in dehydrogenation but also in the decarboxylation and cross coupling reaction. To the best of our knowledge, this is the first example in which different classes of acylated N-heterocycles were directly prepared from the readily available saturated cyclic amines by using 2-oxo-2-arylacetic acids as the noncorrosive and easy to handle acylating reagents. Compared with literature methods, this new protocol has the advantages such as readily obtainable substrates, broad substrate scope, high efficiency, and good selectivity.
- Shi, Xiaonan,Chen, Xi,Wang, Muhua,Zhang, Xinying,Fan, Xuesen
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p. 6524 - 6533
(2018/05/25)
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- Catalytic Friedel-Crafts acylation: Magnetic nanopowder CuFe 2O4 as an efficient and magnetically separable catalyst
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Catalytic regioselective Friedel-Crafts acylation of an array of anisoles/arenes with various acid chlorides using 5-20 mol % of magnetic nanopowder CuFe2O4 is reported. Unlike the conventional Friedel-Crafts reactions, which are catalyzed by moisture sensitive homogeneous catalysts/promoters, the nanopowder CuFe2O4 catalyst is moisture insensitive and the product/ketone-catalyst isolation is easily achieved using the magnetic properties of CuFe2O4.
- Parella, Ramarao,Naveen,Kumar, Amit,Babu, Srinivasarao Arulananda
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p. 1738 - 1742
(2013/03/28)
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- A mild and facile one-pot synthesis of N-methyl-3-acyl- pyrroles
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N-Methyl-3-acylpyrroles were synthesized via a multicomponent reaction of dimethylacetylene dicarboxylate (DMAD), N-methylhydroxylamine and acylchlorides in the presence of KHCO3. For comparison both conventional and microwave protocols were examined in this procedure. The reaction is clean and gives the products in good to excellent yields under conventional heating conditions at 40 °C in anhydrous dichloromethane.
- Valizadeh, Hassan,Fakhari, Ashraf
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experimental part
p. 2972 - 2979
(2010/09/04)
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- A facile, highly efficient synthesis of fully N-confused calix[5]pyrrole
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Fully N-confused calix[5]pyrroles 3 are prepared in high yield by the oligomerization of 3-hydroxyphenylmethylpyrrole 2 under acid-catalysed conditions at room temperature.
- Chen, Qingqi,Wang, Tianyu,Zhang, Yi,Wang, Qiuan,Ma, Jinshi
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p. 1041 - 1049
(2007/10/03)
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- Acylation of Pyrrole and N-Methylpyrrole with 1,3-Benzoxathiolium Tetrafluroborates. A High-Yield Method for the Synthesis of Diacylpyrroles
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2-Substituted 1,3-benzoxathiolium tetrafluoroborates (I) were used as masked acylating agents for pyrrole and N-methylpyrrole.The reactions on pyrrole (II) were regiospecific, and according to the molar ratio of the reagents (I:II = 1:3 or 2.5-3:1), 2-acylpyrroles were obtained in moderate to good yields (38-82percent) and 2,5-diacylpyrroles were obtained in excellent yields (in most cases, quantitative).The reactions on N-methylpyrrole (III) were not regioselective, and both α- and β-positions were attacked.So, depending on the molar ratio of the reagents (I:III = 1:3 or 2,5-3:1), 2- and 3-acyl-N-methylpyrroles (9-51percent and 27-68percent yields, respectively) and 2,4- and 2,5-diacyl-N-methylpyrroles (60-93percent and 17-40percent, respectively) were obtained.A very interesting feature of the new method is the possibility of introducing two identical or different acyl groups in the pyrrole ring under mild conditions. 1H and 13C NMR spectra of all the new compounds and IR spectra, recorded in the gas phase, of 2- and 3-acylpyrroles and of 2,4- and 2,5-diacylpyrroles are reported.
- Barbero, Margherita,Cadamuro, Silvano,Degani, Iacopo,Fochi, Rita,Gatti, Antonella,Regondi, Valeria
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p. 2245 - 2250
(2007/10/02)
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- Acid-Mediated Rearrangement of Acylpyrroles
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N-Alkyl-2-acylpyrroles are converted by strong anhydrous acid to 1-alkyl-3-acylpyrroles.An equilibrium mixture of 2- and 3-acylpyrrole is produced by treatment of a 2- or 3-acyl NH pyrrole with acid.Pyrrolecarboxaldehydes similarly afford isomeric mixtures.A cross-ring migration, 7->8, is observed when the adjacent position is blocked.The mechanism of acid-mediated rearrangement of acylpyrroles is discussed.
- Carson, John R.,Davis, Nancy M.
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p. 839 - 843
(2007/10/02)
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- Preparation of β-acyl pyrroles
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A process for rearranging α-acyl pyrroles to β-acyl pyrroles which comprises reacting the former with an excess of a strong, anhydrous, non-oxidizing acid, preferably with heating.
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