The structure of zeyloxanthonone has been unambiguously established as 1,2,3,4- tetrahydro- 6,8- dihydroxy- 1,1,7- tris (3- methyl but-2- enyl)- xanthene-2,9- dione (1) by 2D NMR spectroscopy, isotopic exchange and chemical reactions.
The long standing controversy of the structure (1 or 2) of zeyloxanthonone has been settled. Unequivocal evidences for structure 1 have been obtained.
A. Banerji, Deshpande, A. D., and Pradhan, P., “Structure of Zeloxanthonone-A Reinvestigation”, Tetrahedron Letters, vol. 32, p. 4995, 1991.