Carbon-13 NMR assignments

Ralph, J. Ede, R. M. NMR of lignin model quinone methides. Corrected carbon-13 NMR assignments via carbon-proton correlation experiments. Holzforschung 1988,42,3 37-338. 

Van Calsteren, M.R., Cormier, F., Chi, B.D., and Laing, R.R. 1991. Proton and carbon-13 NMR assignments of the major anthocyanins from V -tis vinifera cell suspension culture. Spectroscopy 9 1-15. 

Carbon-13 NMR assignments have been made for some of the ring systems under review. Comprehensive data are available for the 2,2-dioxides of pyrazino[2,3-c][l,2,6]thiadiazines (19)... 

Table 5 Complete Proton and Carbon-13 NMR Assignments of the 6-Phenyl-6-deoxy-2,3-di-0-methyl-l,4-anhydrogIucose Repeating Unit...

Ablordeppy SY, Hufford CD, Bourne RF, Dwuma-Badu D (1990) Proton NMR and carbon-13 NMR assignments of cryptolepine, a 3 4-benzo-d-carboline derivative isolated from Cryptolepis sanguinolenta. Planta Med 56 416-417 Alam M, Mroue M (1991) Crooksiine, a bisindole alkaloid from Haplophyton crooksii. Phytochemistry 30 1741-1744... 

G. Blaskd, G.A. Cordell, S. Bhamarapravatl, and C.W.W. Beecher, Carbon-13 NMR assignments of berberlne and sangulnarlne, Heterocycles, submitted for publication. 

The proton decoupled carbon 13 NMR spectra for three poly( cyclohexylmethyl-co-isopropylmethyl) copolymers are shown in Figure 4. The backbone methyl group is observed as occurring between -4 and -1 ppm and consists of multiple resonances which are due to polymer microstructure. Multiple resonances are also observed for the methyl and tertiary carbon of the isopropyl group and for the methine carbon of the cyclohexyl group. Microstruc-tural assignments for these resonances remain to be made. It has also been found that increasing the bulky character of the substituent yielded broader resonance peaks in the carbon-13 NMR spectra. 

The carbon-13 NMR spectra of miconazole nitrate were obtained using a Bruker Instrument operating at 75, 100, or 125 MHz. The sample was dissolved in DMSO-d6 and tetramethylsilane (TMS) was added to function as the internal standard. The 13C NMR spectra are shown in Figs. 9 and 10 and the HSQC and HMBC NMR spectra are shown in Figs. 11 and 12, respectively. The DEPT 90 and DEPT 135 are shown in Figs. 13 and 14, respectively. The assignments for the observed resonance bands associated with the various carbons are listed in Table 4. 

The spectrum is in substantial agreement with the data reported by Wenkert et. al, (6). However, on the basis the proton coupled carbon 13 NMR spectra, the assignments for 6 and 7ot are reversed [Brambilla (16)] from those previously reported. The new assignments are based on long range H-C-O-C couplings. 

M. Shamma and D. M. Hindenlang, Carbon-13 NMR Shift Assignments of Amines and Alkaloids. Plenum New York, 1979. 

Further confirmation of the structure of the AHLs often follows from the determination of their proton and carbon-13 NMR spectra. A large number of AT-acyl, AT-(3-oxoacyl) and AT-(3-hydroxyacyl)-L-HSL derivatives have been prepared and their NMR data reported [14-16]. Also a detailed study by Lao et al. [49] on the complete assignments of the 13C NMR resonances of AT-acyl and N-(3-oxoacyl)-L-HSL derivatives has been published. These assignments were made by comparison with values for AT-butanoyl-L-HSL (C4-HSL), whose structure was comprehensively established by a combination of 1-D and 13C spectra and 2-D COSY,NOESY, HSQC and HMBC experiments. The assignments... 

Vanderlei MF, Silva MS, Gottlieb HF, Braz-Filho R. Iridoids and Triterpenes from Hi-matanthus phagedaenica the Complete Assignment of the Proton and Carbon-13 NMR Spectra of Two Iridoid Glycosides. Journal of the Brazilian Chemical Society 1991 2(2) 51-55. 

The epoxidation reaction was monitored by high performance liquid chromatograph (HPCL) on a reverse phase column. The reaction product was identified by IR, proton NMR and carbon-13 NMR spectroscopy. In the IR spectrum, absorption bands at 904 cm-1 and 842 cm-1 were attributed to the epoxy groups (12) peaks at 2.60, 2.78, and 3.15 ppm on the 1H-NMR spectrum were assigned to the three protons of the epoxide group (13) and in the 13C-NMR spectrum, the three glycidyl carbons were identified at 44.5, 50.6, and 70.6 ppm (14). 

The present catalogue provides proton and/or carbon-13 NMR chemical shift assignments and physical constants for many of the naturally occurring diterpenoid alkaloids and their derivatives. The literature search is not intended to be exhaustive. It is hoped that the 13C NMR data bank will serve as a useful guide for determining the structures of newly isolated alkaloids. 

The broad band decoupled carbon-13 NMR spectrum of cimetidine hydrochloride (Figure 3) was obtained by using a solution of approximately 100 mg/ml in deuterated dimethylsulf oxide. The deuterium signal of dimethylsulfoxide was used as the internal reference and the spectrum was obtained on a Varian Associates Model FT-80 fourier transform NMR spectrometer. The chemical shift assignments are ... 

The same type of information was obtained from proton and carbon-13 NMR. Once again there are absorptions that may be due to carbon and hydrogen bonded to sulfur but contributions from other non-sulfur containing structures are highly likely and hence a firm assignment cannot be made. 

Carbon-13 NMR spectra have been routinely recorded for 1,2- and 1,3-diazetidine derivatives for their spectral assignment. Data for a few diazetidines are collected in Table 11. 

Johnson, L. F., and Jankowski, W. C. (1972). Carbon-13 NMR Spectra, a Collection of Assigned, Coded, and Indexed Spectra. New York Wiley. 

Carbon-13 NMR of l-propyllithium-13Ci—6Li, 13, in cyclopentane at 200 K, showed resonances for five species assigned from the multiplicities and splittings of their 13C... 

Proton and carbon 13 NMR spectra were obtained from the three commercial samples. A series of unknown spectral components were observed in product A at 3.68 ppm, 3.98 ppm, 4.08 ppm, 4.15 ppm, 5.05 ppm, and 5.17 ppm. Comparison of the unknown peaks with the spectra of MAGs indicated that most of the observed peaks correlated with those present in the spectra of MAGs. An exact assignment of the spectra was not attempted as many forms of MAGs are possible. Observation of the spectral region of the olefinic protons revealed that the three samples were... 

Johnson LRF, Jankowski WC (1972) Carbon-13 NMR spectra. A collection of assigned, coded and indexed spectra. WUey, New York... 

The carbon-13 NMR spectrum shown in Figure 5 was obtained using a 200 mg/mL solution of indapamide in deuterated methanol. Figure 5 also shows the structural numbering of indapamide to facilitate carbon NMR spectral assignments. The carbon-13 NMR spectrometer parameters and tentative spectral assignments are listed in Tables IV and V, respectively. 

Asakura, T. Nakayama, N. Demura, M. Asano, A. Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations. Macromolecules 1992, 25, 4876-4881. 

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