High-Field Nmr-Study Of The Tautomers Resulting From The Condensation Of 2-Methylindole And Phenalenone In The Presence Of Para-Toluenesulphonic Acid

As phenalene is an alternant hydrocarbon it is oxidized very easily to phenalenone, which condenses with various nitrogen nucleophiles in the presence of p-toluenesulphonic acid. 2-Methylindolylphenalene is obtained with 2-methylindole, together with other products. This product is a mixture of five tautomers in equilibrium, and these were analysed by homo- and heteronuclear two-dimensional high-field NMR (500 MHz) spectroscopy.