- A direct, regioselective palladium-catalyzed synthesis of N-substituted benzimidazoles and imidazopyridines
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Unsymmetric, N-substituted benzimidazoles and imidazopyridines can be prepared directly from 2-halonitroarenes and amides through Pd(TFA) 2/(R)-BINAP-catalyzed cross-coupling and subsequent reductive aminocyclization. This sequence can be conducted by a one-pot procedure. The method is versatile and allows the straightforward, regioselective preparation of these important nitrogen heterocycles. Unsymmetrical, N-substituted benzimidazoles can be prepared directly from 2-halonitroarenes and amides through Pd(TFA)2/(R)-BINAP-catalyzed cross-coupling and subsequent reductive aminocyclization.This sequence can be conducted by a one-pot procedure. The method is versatile and allows the straightforward, regioselective preparation of these important nitrogen heterocycles. Copyright
- Alonso, Jorge,Halland, Nis,Nazare, Marc,R'Kyek, Omar,Urmann, Matthias,Lindenschmidt, Andreas
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supporting information; experimental part
p. 234 - 237
(2011/03/20)
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- Amino acid-mediated Goldberg reactions between amides and aryl iodides
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A highly general, experimentally simple, and inexpensive catalyst system was developed for the amidation of aryl iodides by using 5mol% of CuI as catalyst, 20mol% of an amino acid as ligand, and K3PO4 as base.
- Deng, Wei,Wang, Ye-Feng,Zou, Yan,Liu, Lei,Guo, Qing-Xiang
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p. 2311 - 2315
(2007/10/03)
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- DBU, a highly efficient reagent for the facile regeneration of (hetero)arylamines from their acetamides and benzamides: Influence of solvent, temperature, and microwave irradiation
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1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) was found to smoothly cleave the N-acetyl and N-benzoyl derivatives of carbazoles, indoles and nitroanilines quickly in refluxing methanol and the parent amines were recovered in excellent yields. Complete cleavage could also be accomplished in acetonitrile solution under reflux and also under microwave irradiation, which, however, required considerably longer periods.
- Chakrabarty, Manas,Ghosh, Nandita,Khasnobis, Shampa,Chakrabarty, Manju
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p. 265 - 272
(2007/10/03)
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- Chemical and Electrochemical Reduction of ortho-Nitroanilides. A Combined Chemical, Polarographic and EPR Study
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The acetyl and benzoyl o-nitroanilines 1a and 1b and the acetyl and benzoyl o-nitrodiphenylamines 1c and 1d have been reduced chemically (t-BuOK/DMSO) and electrochemically inside the cavity of an EPR spectrometer.For all compounds the EPR signal of the radical anions could be recorded and interpreted.In DMSO the radical anions 1c(1-) and 1d(1-) evolved to the phenazine radical anion within 1 h.The polarographic study showed that the four compounds are reduced in two different steps, the first being monoelectronic and reversible, as demonstrated by cyclic voltammetric experiments.Compounds 1a-d were reduced with Fe/AcOH to the benzimidazoles 5a-d.The catalytic reduction of 1a gave the hydroxy-2-methylbenzimidazole 7a together with the azoxy derivative 6a.The macroscale electrolysis of 1c and 1d may be regarded as a convenient synthetic method of preparing benzimidazoles 5c and 5d, while the catalytic reduction may be considered the best route to benzimidazole N-oxides 4c and 4d.
- Alberti, Angelo,Carloni, Patricia,Greci, Lucedio,Stipa, Pierluigi,Andruzzi, Romano,et al.
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p. 1019 - 1023
(2007/10/02)
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