Pyrrole studies. Part XVI. Conformational studies of 6-aryl-6-di-methylamino-2-azafulvenes [2-aryl(dimethylamino)methylenepyrroles]

Abstract

The energy barriers to rotation about the C(6)–N bond of a series of 6-p-substituted phenyl-6-dimethylamino-2-azafulvenes have been studied by n.m.r. spectroscopy and have been found to have values in the range 58·58 to 64·43 kJ/mol. The lack of a correlation between the electronic effect of the para-substituent and the rotational-energy barriers suggest a lack of coplanarity between the rings with a consequent reduction in the cross conjugation within the system.