Location of alkoxylation sites in naturally occurring xanthones

Abstract

The 1 H nmr spectra of acetoxyxanthone and alkoxyxanthone show that there is a large change in chemical shift of aromatic proton which is para to the site of difference In the absence of a para proton, ortho protons undergo large change in chemical shifts. This change is helpful in locating alkoxylation site in naturally occurring xanthones.