0000000001036080
AUTHOR
Marcella Pani
Synthesis of trifluoromethylated 2-benzoyl- and 2-aminoimidazoles from ring rearrangement of 1,2,4-oxadiazole derivatives
Abstract Fluoroalkylated 2-ylamino-imidazoles have been synthesized by reaction of 3-amino-5-phenyl-1,2,4-oxadiazole with fluorinated β-dicarbonyl compounds and subsequent base-induced Boulton–Katritzky Rearrangement (BKR) of the isolated β-enaminocarbonyl intermediate. Alternatively, one-pot reactions performed in the presence of Montmorillonite K10 favoured the condensation at the 3-amino moiety of the oxadiazole and, in some cases, allowed the direct synthesis of 2-benzoylamino-imidazoles. Hydrolysis of 2-benzoylamino-imidazoles easily yielded fluorinated 2-amino-imidazoles targets.
On the structure of 3-acetylamino-5-methyl-1,2,4-oxadiazole and on the fully degenerate rearrangements (FDR) of its anion: a stimulating comparison between the results of ‘in-silicon chemistry’ and ‘laboratory chemistry’
An accurate crystal structure determination has provided evidence for a planar conformation for 3-acetylamino-5-methyl-1,2,4-oxadiazole (5), in agreement with quantum-mechanical calculations in the gas phase. In the crystal, a series of strong intermolecular N7H7….O9 hydrogen bonds link the amido groups of different molecules, causing the formation of infinite parallel ordered chains. The effect of the DMSO solvent on the energy and charge distribution of compound 5 and on its relevant 5− anion, involved in a fully degenerate rearrangement (FDR), has been deepened by quantum-mechanical DFT calculations. The calculated energy barrier for the FDR increases in going from in vacuo to DMSO, in a…
One-pot synthesis of fluorinated 2-amino-pyrimidine-N-oxides. Competing pathways in the four-atom side-chain rearrangements of 1,2,4-oxadiazoles
Abstract Trifluoromethylated 2-amino-pyrimidine N-oxides have been synthesized by reaction of the 3-amino-5-methyl-1,2,4-oxadiazole with trifluoromethyl-β-diketones in the presence of perchloric acid, followed by hydrolysis. In this ring-to-ring transformation an initial formation of (unisolated) 1,2,4-oxadiazole-pyrimidinium salts, and subsequent ring-opening at the oxadiazole moiety occurs. Isolation of 2-(hydroxyamino)-pyrimidine from the reaction mixture evidenced the presence of a competing pathway where the N(4) nitrogen of the oxadiazole is involved in the formation of a regioisomeric pyrimidinium salt. The effect of the trifluoromethyl group on the product distribution is discussed.…
ChemInform Abstract: Synthesis of Trifluoromethylated 2-Benzoyl- and 2-Aminoimidazoles from Ring Rearrangement of 1,2,4-Oxadiazole Derivatives.
Abstract Fluoroalkylated 2-ylamino-imidazoles have been synthesized by reaction of 3-amino-5-phenyl-1,2,4-oxadiazole with fluorinated β-dicarbonyl compounds and subsequent base-induced Boulton–Katritzky Rearrangement (BKR) of the isolated β-enaminocarbonyl intermediate. Alternatively, one-pot reactions performed in the presence of Montmorillonite K10 favoured the condensation at the 3-amino moiety of the oxadiazole and, in some cases, allowed the direct synthesis of 2-benzoylamino-imidazoles. Hydrolysis of 2-benzoylamino-imidazoles easily yielded fluorinated 2-amino-imidazoles targets.
On the structure of 3-acetylamino-5-methyl- 1,2,4-oxadiazole and on the fully degenerate rearrangements (FDR) of its anion: a stimulating comparison between the results of ‘in-silicon chemistry’ and ‘laboratory chemistry’
An accurate crystal structure determination has provided evidence for a planar conformation for 3-acetylamino-5-methyl-1,2,4-oxadiazole (5), in agreement with quantum-mechanical calculations in the gas phase. In the crystal, a series of strong intermolecular N7H7...O9 hydrogen bonds link the amido groups of different molecules, causing the formation of infinite parallel ordered chains. The effect of the DMSO solvent on the energy and charge distribution of compound 5 and on its relevant 5S anion, involved in a fully degenerate rearrangement (FDR), has been deepened by quantum-mechanical DFT calculations. The calculated energy barrier for the FDR increases in going from in vacuo to DMSO, in …