Structure of 8-(2,6-dideoxy-beta-ribo-hexopyranosyl)-5-hydroxy-2-(4- hydroxyphenyl)-7-methoxy-4H-1-benzopyran-4-one sesquihydrate, aciculatin.

C22H22O8.1.5H2O, Mr = 441.4, monoclinic, I2, a = 21.037 (7), b = 7.371 (2), c = 27.512 (4) A, beta = 100.34 (2) degrees, V = 4196.8 (8) A3, Z = 8, Dx = 1.397 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.029 cm-1, F(000) = 1864, T = 295 K, final R (on F) = 0.058 for 2113 observed reflections with I greater than or equal to 2 sigma (I). Aciculatin crystallizes as a sesquihydrate with two independent molecules per asymmetric unit. The 2,6-dideoxy-beta-ribo-hexopyranosyl ring is linked to C8 of the flavone through a beta-C-glycosidic bond. Intramolecular hydrogen bonding occurs between the hydroxyl and ketonic O atoms of the flavone ring system.