THE STRUCTURE DETERMINATION OF SIMONYELLIN - A NEW LICHEN NAPHTHOPYRAN

The structure of simonyellin dihydroxy-4-methoxy-7-methyl-1H,6H-naphth o[1,8-cd] pyran-1,6-dione), a naphthopyran from the lichen Simonyella variegata Steiner, has been established by X-ray structure analysis of a corresponding tetraacetate derivative. Crystals of simonyellin tetr aacetate are triclinic, <P(1)over bar>, a 10.974(2), b 11.282(3), c 20 .634(3) Angstrom, alpha 92.23(2)degrees, beta 100.03(1)degrees, gamma 117.80(2)degrees; Z 4. Refinement of 2754 data with I > 3 sigma(I) gav e conventional R factors of 0.043 and 0.034.