Unequal aromatic resonance contributions detected by nuclear overhauser effect difference spectroscopy of aromatic methyl ethers

Abstract

Nuclear Overhauser effect difference spectra of aryl methyl ethers reveal a striking conformational preference for the methoxy-groups s-cis to the ortho-position with the highest double bond character; this conformational preference correlates with the positional reactivity of the aromatic ring and its interpreted as arising from dissimilar resonance contributions.