13C- and ’H-NMR chemical shift assignments

Total assignment of the H and 13C NMR chemical shifts as well as the relative configuration of the Diels-Alder adducts 33-35 was accomplished with the help of 2D (111-111 COSY, H-111 NOESY (NOESY = nuclear Overhauser enhancement spectroscopy), H- C XHCORR (XHCORR = nucleus X-hydrogen correlation), H-13C COLOC) and NOE difference spectroscopy <1996JHC697>. 

The H-NMR and 13C-NMR chemical shifts for representative 2-aminofurans are shown in Tables 2 and 3. 13C-NMR data are very limited and assignments of signals are often not included with the chemical shifts. 

An analogous approach has been used in assigning H and 13C NMR chemical shifts in anthracenedione phenylhydrazones,50 l,3-bis(phenylazo)-2-naphthol and its precursors.51 Azo and hydrazone compounds 13 derived from Fischer base (l,3,3-trimethyl-2-methylidene-2,3-dihydroindole) were studied by two groups.52,53 

Berger and Diehl90 have assigned the 1H and 13C NMR spectra of 2-substituted anthracenes based on H-13C HMQC measurements11,12. The H and 13C NMR chemical shifts for 2-aminoanthracene are given in Table 11. 

Compounds 1 and 2 were identified by FTIR and 13C-NMR. The 13C proton decoupled spectra for 1 and 2 are dominated by signals ranging from 62 to 195 ppm. The 13C chemical shift assignments were made based on comparisons with 4,4 -(hexafluoroisopropylidene)diphenol and from calculations based on substituted benzenes and naphthalenes.15 The 13C-NMR spectrum clearly showed that the Friedel-Crafts acylation of 1 by 4-fluorobenzoyl chloride yielded the 1,4-addition product exclusively. The 13C chemical shifts for 2 are listed in Table 8.1. The key structural features in the FTIR spectrum of2 include the following absorptions aromatic C-H, 3074 cnr1, ketone C=0, 1658 cm-1, aromatic ether Ar—0—Ar, 1245 cm-1, and C—F, 1175 cm-1. 

Structure elucidation of phenylethanoid glycosides were carried out on the basis of spectral analysis and chemical evidences. Assignment of the 13C-NMR chemical shifts of phenylethanoid glycosides were re-examined and shown in Table 2. [24] Two dimensional NMR spectra, such as HfCOSY), H- 

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