NMR spectral studies of quinoline derivatives. Long range <sup>13</sup>C<sup>1</sup>H coupling constants in methylquinoline derivatives

Claret, P. A.; Osborne, Alan G.

doi:10.1002/mrc.1270080309

Cited by 39 publications

(13 citation statements)

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“…This area corresponds to C 4 –H 4 correlations of quinoline derivatives alkylated in position 5. The lower chemical shifts δ C 4 of A5″ are validated in the literature where δ C 4 for 5,8-dimethylquinoline, 5,7-dimethylquinoline, and 5-methylquinoline are measured at 131.9, 132.4, and 132.7 ppm, respectively. In A5″, few signals are more deshielded in 1 H than quinoline.…”

Section: Resultssupporting

confidence: 57%

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Proriol

Chahen

2020

Energy Fuels

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Basic nitrogen compounds (N-compounds), present in middle distillates, can inhibit acidic catalysts used in hydrotreatment processes. A better knowledge of these compounds, especially the environment of the nitrogen atom, may be interesting to improve these processes. Herein, we propose a new promising methodology to couple the extraction of the basic N-compounds by flash chromatography with 2D NMR analysis. The NMR sequence heteronuclear single-quantum correlation (HSQC) allows us to visualize specific C–H correlations and, with the help of the prediction software Advanced Chemistry Development/Laboratory (PS-ACDL), eleven areas of interest have been identified. The representativeness of these areas has been validated with data from literature and with a gas oil (GO) sample analysis. These areas are specific to C–H couples in pyridine, quinoline, isoquinoline, and acridine derivatives and give a detailed fingerprint of basic N-compounds in the GO cut. Moreover, certain areas allow us to describe the close environment of the nitrogen atom and allow, for example, to differentiate isoquinoline from quinoline derivatives.

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Section: Resultssupporting

confidence: 57%

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Proriol

Chahen

2020

Energy Fuels

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“…The structural assignment of the synthetic product 1 was supported by the similarity of its spectral data with those of acrophylline (7) (5). The ir spectrum of compound 7 has a carbonyl absorption band at 1620 cm-1, and its 'H-nmr spectrum exhibits absorptions at 6.83 (m, 2H) and 8.31 (d, 1H) for the protons of the benzene ring, in addition to those at 7.22 and 6.99 for the protons of the furan ring.…”

mentioning

confidence: 85%

“…Thermal cyclization of 3 in boiling diphenylether afforded 7-methoxy-2,3,4,9-tetrahydrofuro(2,3-¿)quinolin-3,4-dione (4a) in 86% yield. Thespectrum of 4aexhibits, besides two singlets at 8 4.10 and 5.24, a single-proton absorption at 8.36, which is coupled only to the proton at 7.31 (/-9.0 Hz), and a one-proton signal at 7.23, which is also a singlet. This observation is consistent with the substitution pattern of the benzene ring in structure 4a and thus excludes the other possible cyclized product 4b.…”

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confidence: 99%

“…In order to gain further insight into the structure of the synthetic product, its 13Cnmr spectrum was obtained, and the data is summarized in Table 1. Assignments of the 13C-nmr spectrum were made possible by comparison with model compounds [furoquinoline alkaloids (6), quinolin-4-ones (7), and benzofurans (8)] and by decoupling techniques. Thus, the assignments of sp2-hybrid methine carbons (C-2, C-3, C-5, C-6, and C-8) were made in accordance with the multiplicity (doublet) and the chemical shift of the ß-carbon of anisóle and furan, which appears at higher field than the carbon directly bonded to oxygen ( -carbon) (9).…”

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confidence: 99%

“…We have also found that reduction of 4a with NaBH4 in ethanolic alkali proceeded to afford directly the furoquinolinone 10 in 54% yield (10,11). 'H-nmr 1.63 (t,3H,y=7.0 Hz) I.48(t, 3H,_/=7.0 Hz, CH2C/i3) 1.52(t, 3H,7=7.0Hz) ppm 4.77 (q, 1H,7=7.0 Hz) 4.11 (q, 2H,7=7.0 Hz, CH2CH,) 4.57(q,2H,7=7.0Hz) (CDCl,) 3.97 (s,3H) 3-94(s, 3H, OCH3) 3.92 (s,3H) 7.00(d, 1H) 7.05 (d, lHJ=2.5Hz, 3-H) 6.83 (d, 1H,7=2.5 Hz) 7.65 (d, 1H) 7.27 (d, lHJ=2.5Hz, 2-H) 7.29UH, d,7=2.5 Hz) 7.38(dd, lH,y=9.0Hz;3Hz) 6.95 (lH.d,7=9.0Hz,6-H) 7.03 (1H, dd,7=9 Hz, 2.5 Hz) 7.60(d, 1 ,_/=3 Hz) 6.87 (1H, s, 8-H) 7.46(lH,d,7=2.5Hz) 8.00(d, lHJ=9-0Hz) 8.50(d, 1 ,7=9.0 , The structure assignment to compound 8 follows reasonably from its origins. Further, its 'H-nmr spectrum is completely consistent with the structure.…”

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confidence: 99%

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Studies on Heterocyclic Compounds, VI. Synthetic Investigation of Taifine

Kuo¹,

Lin²,

Chang³

et al. 1986

J. Nat. Prod.

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A synthetic approach to the structure reported for the naturally isolated alkaloid named taifine has been developed. The structural assignment is established by spectral data: ir, uv, nmr, and 13C nmr. However, both the spectral and physical properties indicate that synthetic and natural taifine are different in constitution, suggesting the original structure assigned for taifine should be revised.Recently, a novel furo(2, 3-¿)quinolin-4-one named taifine was isolated from Ruta chalepensis L. (Rutaceae) by El-Tawil and co-workers, and was assigned the structure 9ethyl-7-methoxy-4,9-dihydrofuro(2,3-¿)quinolin-4-one (1) purely based upon spectral data (2). As part of our continuing interest in the synthesis and biological activities of furo(2,3-¿)quinolin-4-one derivatives (1), we carried out a synthetic approach to the structure reported for taifine using the modified procedure of Tuppy and Bóhm (3). We now report the results from this synthetic investigation which suggest that the proposed structure for taifine needs reinvestigation. SYNTHETIC RESULTS AND DISCUSSIONThe synthetic approach to taifine is shown in summary form in Scheme 1. Ethyl Scheme 1 'For Part V, see Kuo et al. (1).

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Alkylquinolines and Arylquinolines

Claret

Osborne

1982

Chemistry of Heterocyclic Compounds: A Series of Monographs

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NMR spectral studies of quinoline derivatives. Long range ¹³C¹H coupling constants in methylquinoline derivatives

Abstract: Abstract-Long range 13C-IH coupling constants are reported for a number of methylquinoline derivatives. The results have been compared with those observed in the pyridine series and correlated with lH--'H coupling constants.

Cited by 39 publications

References 10 publications

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Studies on Heterocyclic Compounds, VI. Synthetic Investigation of Taifine

Alkylquinolines and Arylquinolines

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NMR spectral studies of quinoline derivatives. Long range 13C1H coupling constants in methylquinoline derivatives

Abstract: Abstract-Long range 13C-IH coupling constants are reported for a number of methylquinoline derivatives. The results have been compared with those observed in the pyridine series and correlated with lH--'H coupling constants.

Cited by 39 publications

References 10 publications

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Toward New Descriptors of Basic Nitrogen Compounds in Middle Distillates by 2D NMR

Studies on Heterocyclic Compounds, VI. Synthetic Investigation of Taifine

Alkylquinolines and Arylquinolines

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NMR spectral studies of quinoline derivatives. Long range ¹³C¹H coupling constants in methylquinoline derivatives