The heartwood chromones of Cedrelopsis grevei

Abstract

The heartwood of Cedrelopsis grevei Baill. is shown to contain the known chromones heteropeucenin, alloptaeroxylin, ptaeroglycol, and peucenin. It also contains three new ones, greveichromenol, greveiglycol, and alloptaeroxylin methyl ether, and possibly a fourth, a methyl ether of greveiglycol which, however, may be an artefact. Greveichromenol is allocated structure (VIa) on spectroscopic grounds together with a conversion into isopeucenin. Greveiglycol (VIIIa) and the methyl ether (VIIIb) are allocated these structures on spectroscopic grounds together with syntheses from alloptaeroxylin methyl ether. A long range coupling is noted between the protons of the methyl group and the proton at position 3 in derivatives of 2-methylchromone, but it seems variable in magnitude and therefore of limited diagnostic value. Comparisons of the pyrones of divers samples of the heartwoods of Cedrelopsis grevei and of Ptaeroxylon obliquum show that these are closely related species but that their constituents are unsuitable for more detailed taxonomic purposes. P. obliquum has been found to contain peucenin 7-methyl ether, overlooked in the earlier study, and not previously encountered as a natural product.