General method for the assignment of stereochemistry of 1,3-disubstituted 1,2,3,4-tetrahydro-.beta.-carbolines by carbon-13 spectroscopy

A Convenient Synthesis of Indole-Substituted 2-Pyrrolidones and Their Cyclized Derivatives

“…We also noticed that, in the case of compound 19a, the 13 C NMR signals of C-5 and C-3a appear downfield compared to those of 20a (see Experimental Section). This is in accordance with Cook's results [14,15] concerning 1,3-disubstituted tetrahydro-β-carbolines.…”

Total Synthesis of (–)‐Corynantheidine by Nickel‐Catalyzed Carboxylative Cyclization of Enynes

“…As expected, the stereochemistry of the major product was unambiguously assigned to have the cis configuration by comparison of its 13 C NMR spectrum with that of the minor product, in which the 13 C carbon signals for C1 and C3 of the major product [cis-9: δ = 53.2 (C1), 56.8 (C3) ppm] were downfield relative to those of the minor product [trans-9: δ = 48.9 (C1), 52.1 (C3) ppm]. [9] Scheme 3. cis-Selective Pictet-Spengler reaction.…”

Synthesis of Novel Tadalafil Analogues and their Evaluation as Phosphodiesterase Inhibitors and Anticancer Agents

“…This is confirmed by the matching physicochemical properties of the isomers obtained from I, II, III or IV indicating their enantiomeric nature. Such has been re-ported previously [11,12].The assignment of cis/trans stereochemistry for tetrahydro-β-carbolines was based on a detailed study of 1 H and 13 C NMR spectroscopy and by comparison with the literature data [13,14].…”

“…FTIR spectra were recorded on Nicolet Avatar 380 spectrometer (Thermo Scientific, Waltham, MA, USA). 1 H-NMR spectra were recorded on Varian Mercury VX-300 MHz spectrometer (Varian, Palo Alto, CA, USA) using CDCl 3 as a solvent; 13 …”