¹³C NMR spectroscopy of indole derivatives

Conformational studies on indole alkaloids from Flustra foliacea by NMR and molecular modeling

“…The 13 C values agreed with the literature. 6 Dealing with the HMBC spectra of 1a, 1b, 2a and 2b, the signal at υ 7.0 š 0.12, assigned to H-4, shows cross peaks with C-6 and the non-protonated carbons C-3a and C-7a. From the HSQC and proton spectra, the corresponding proton signal of the characteristic methine carbon C-8a (υ 86.9 š 2.5) is the singlet at υ 4.36 š 0.03.…”

Complete 1H NMR assignment of 3‐formylindole derivatives

“…, bottom) as a consequence of the anisotropic effect of the carbonyl group substituent at the N1 position . Another useful option to differentiate between the H4 and H7 signals would be, provided adequate solubility, the correlation with their respective carbon atoms in 1 J C–H correlated spectra because in indole derivatives, C7 has a significant upfield shift relative to all other protonated benzenoid carbon atoms . In the case of 7, it is important to note that the crystal structure (Fig.…”

Gluco-indole alkaloids from the bark ofNauclea diderrichii.1H and13C NMR assignments of 3?-5?-tetrahydrodeoxycordifoline lactam and cadambine acid

“…The NDc (3 g) was subjected to reversed-phase LPC (Jobin-Yvon RP18) using a gradient of MeOH in H 2 O to afford 13 15 four methines and two methylene groups. 13 C NMR chemical shifts and HMBC correlations for aromatic carbons (Scheme 1) were characteristic of a tetrahydro-ˇ-carboline ring 16,17 In the HMBC spectrum a correlation peak was observed between the anomeric proton and the C-21 of the alkaloid part, thus identifying the point of attachment of the sugar. Further analysis of the 13 C NMR data revealed the presence of eight aromatic carbons (four CH and four C), one trisubstituted olefin (υ H 7.34,s; υ C 150.57) Gluco-indole alkaloids from bark of Nauclea diderrichii The occurrence of the subunit CH 2 CHCH(CH)CHCH 2 followed from the complete analysis of the COSY diagram.…”