3-Hydroxypyrroles and 1H-pyrrol-3(2H)-ones. Part 5. Tautomerism of 1-substituted and 1,2-disubstituted derivatives in the solid state and in solution: X-ray crystal and molecular structure of 1-phenyl-1H-pyrrol-3(2H)-one

Abstract

X-Ray crystallography of the typical derivative 1-phenyl-1H-pyrrol-3(2H)-one (6) has shown that the title compunds exist in the solid state as keto tautomers. In solution, the influence of solvent polarity, hydrogen bonding to solvent, and the steric and electronic demands of substituents on the position of the keto–enol equilibrium have been determined by n.m.r. spectroscopy for a number of examples.