Relaxation processes in aromatic methyl groups. ii: Methyl-methyl nuclear overhauser enhancements

Abstract

A range of compounds with methyl groups disposed ortho and peri on heteroaromatic frameworks have been prepared, and T1 values and methyl-methy! Overhauser effects measured for them. Most of the n.O.e. values were =6%, but two examples of methyls flanked by two others exhibited values of 9% (6-hydroxy-4, 4, 5, 7-tetramethyl-3, 4-dihydro-2H- benzopyran-2-one) and 15% (1, 4, 5, 8, 9-pentamethylcarbazole). © 1990 ASEG.