Acta Cryst. (2002). C58, o195-o198 [ doi:10.1107/S0108270102000689 ]
Abstract: A low-temperature structure of ginkgolide A monohydrate, (1R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11aS)-3-(1,1-dimethylethyl)-hexahydro-4,7b-dihydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione monohydrate, C20H24O9·H2O, obtained from Mo K data, is a factor of three more precise than the previous room-temperature determination. A refinement of the ginkgolide A monohydrate structure with Cu K data has allowed the assignment of the absolute configuration of the series of compounds. Ginkgolide C sesquihydrate, (1S,2R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11S,11aR)-3-(1,1-dimethylethyl)-hexahydro-2,4,7b,11-tetrahydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione sesquihydrate, C20H24O11·1.5H2O, has two independent diterpene molecules, both of which exhibit intramolecular hydrogen bonding between OH groups. Ginkgolide J dihydrate, (1S,2R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11aS)-3-(1,1-dimethylethyl)-hexahydro-2,4,7b-trihydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione dihydrate, C20H24O10·2H2O, has the same basic skeleton as the other ginkgolides, with its three OH groups having the same configurations as those in ginkgolide C. The conformations of the six five-membered rings are quite similar across ginkgolides A-C and J, except for the A and F rings of ginkgolide A.
Formula: C20H24O9·H2O, C20H24O11·1.5H2O and C20H24O10·2H2O
Structure factor file (CIF format) (203.1 kbytes)
Structure factor file (CIF format) (289.9 kbytes)
Structure factor file (CIF format) (132.3 kbytes)
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