The catalytic action of BF3 in the cycloaddition of benzonitrile oxide with nitriles and carbonyl compounds

Morrocchi, S.; Ricca, A.; Velo, L.

doi:10.1016/s0040-4039(00)71544-9

Cited by 60 publications

(35 citation statements)

References 8 publications

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“…give the 4-hydroxy-4,5-dihydro-l ,2,4-oxadiazoles 8 (Scheme-2) (20). The characterization data of synthesized compounds 4a-r are given in the experimental section.…”

Section: Resultsmentioning

confidence: 99%

Heterocyclic Synthesis Using Nitrilimines: Part 7. Synthesis of Some New Substituted 1,2,4,8-TETRAAZASPIRO[4.5]DEC-2-ENES

Dalloul¹,

Boyle²

2007

Heterocyclic Communications

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“…give the 4-hydroxy-4,5-dihydro-l ,2,4-oxadiazoles 8 (Scheme-2) (20). The characterization data of synthesized compounds 4a-r are given in the experimental section.…”

Section: Resultsmentioning

confidence: 99%

Heterocyclic Synthesis Using Nitrilimines: Part 7. Synthesis of Some New Substituted 1,2,4,8-TETRAAZASPIRO[4.5]DEC-2-ENES

Dalloul¹,

Boyle²

2007

Heterocyclic Communications

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“…However, reaction with benzonitrile in the presence of the appropriate catalyst [5] afforded oxadiazolyl-imidazole 7 in moderate yield.…”

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confidence: 99%

Synthesis of 3‐imidazolylazole derivatives from a new nitrile oxide

Foti¹,

Grassi²,

Risitano³

et al. 2001

Journal of Heterocyclic Chem

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The synthesis of a series of 3-Imidazolylazole derivatives using cycloaddition reactions of a useful new nitrile oxide is described.J. Heterocyclic Chem., 38, 539 (2001).Imidazole chemistry continues to be an intense investigative area since a large number of natural and synthetic compounds are associated with this class of heterocycle. For example, many naturally occurring imidazoles have remarkable biological activity, and a large number of synthesised compounds are widely used as antibacterial drugs and in cancer therapy [2].The idea of employing an isoxazole or an oxazole substrate, which are widely used by pharmaceutical and agricultural industries, combined with an imidazole ring to obtain more complex heterocycle compounds, led us to design and synthesise the N-methyl-2-imidazolyl nitrile oxide 4. The new nitrile oxide allowed us to prepare, via a 1,3 dipolar cycloaddition with selected substrates, 3-imidazolyl, 5-membered N,O-heterocycles.The 1,3-dipole was synthesised starting from the aldehyde 1 [3] using a three-step procedure (70% overall yield): oxime 2 formation followed by chlorination to 3 and subsequent in situ generation of 4 by dehydrohalogenation with triethylamine.Cycloaddition reactions were performed on selected electron-rich or electron-poor dipolarophiles using diethyl ether as solvent. As expected, the cycloaddition with monosubstituted dipolarophiles showed high regioselectivity, giving only the 5-substituted derivatives 5 and 6 where the oxygen atom is bound to the more hindered terminus of the dipolarophilic site [4]. The relative yields, which are not optimized are in the range of 30-57%.Attempted cycloaddition of the nitrile oxide with nonconjugated nitriles such as acetonitrile and phenylacetonitrile was unsuccessful. However, reaction with benzonitrile in the presence of the appropriate catalyst [5] afforded oxadiazolyl-imidazole 7 in moderate yield.Attempts to oxidise the isoxazoline rings to the isoxazole derivatives, using literature methods employing MnO 2 and NiO 2 [6], were unsuccessful and the required products were not isolated. EXPERIMENTALMelting points were determined with Reichert-Kofler hot stage apparatus and are uncorrected. IR spectra were obtained on Nicolet FT-IR Impact 400D spectrometer, mass spectra were acquired using a Finnigan Mat 90 spectrometer and the microanalyses for C, H, and N on a Carlo Erba 1102. 1 H NMR spectra were recorded on a Bruker ARX 300 spectrometer, in the solvent indicated. Chemical shifts (δ) are relative to TMS, which was used as an internal reference. Column chromatography was performed on Merck silica gel 70-270 mesh. All solvents and reagents were obtained from commercial sources and purified before use if necessary. Preparation of 2-Imidazolyloxime (2).A solution of 20.85 g of NH 2 OH . HCl in 30 ml of water and 60 ml of a 20% NaOH were added to 5.5 g, 0.05 mol of N-methyl-2-formylimidazole in 150 ml of ethanol. The mixture was heated to boiling for a few minutes, and subsequently the alcohol was evaporated under reduced pressure. T...

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“…Cycloadditions of organic azides to nitrilium salts 1 lead to trisubstituted tetrazolium salts. [8][9][10][11] These reactions are dominated by a concerted mechanism. 9 However, the cycloaddition of the azide ion N 3 -to nitrilium ions is assumed to proceed via a two-step mechanism.…”

Section: Figurementioning

confidence: 99%

2,3,4,5-Tetrahydro-2,4-diimino-1,3,5-triazin-1-ium salts in the reaction of carbodiimides with N-alkylnitrilium salts

Abu‐El‐Halawa¹

2008

Arkivoc

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The catalytic action of BF3 in the cycloaddition of benzonitrile oxide with nitriles and carbonyl compounds

Cited by 60 publications

References 8 publications

Heterocyclic Synthesis Using Nitrilimines: Part 7. Synthesis of Some New Substituted 1,2,4,8-TETRAAZASPIRO[4.5]DEC-2-ENES

Heterocyclic Synthesis Using Nitrilimines: Part 7. Synthesis of Some New Substituted 1,2,4,8-TETRAAZASPIRO[4.5]DEC-2-ENES

Synthesis of 3‐imidazolylazole derivatives from a new nitrile oxide

2,3,4,5-Tetrahydro-2,4-diimino-1,3,5-triazin-1-ium salts in the reaction of carbodiimides with N-alkylnitrilium salts

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