Nuclear Magnetic Resonance Spectroscopy. ^(13)C Spectra of Indole and Methylindoles

The natural-abundance ^(13)C nmr spectra of indole, the seven monomethylindoles, and some di- and trimethylindoles have been determined at 15.1 MHz. The chemical shifts of the ring carbons in these compounds were found to range over 50 ppm, and with the aid of complete proton decoupling it was possible to resolve all of the carbon resonances. Single-frequency and off-resonance proton-decoupling techniques were employed to assign the resonances to specific carbons.