Humilinolide D

The title molecule, methyl [alpha],10-bis(acetoxy)-4-(3-furanyl)-1,4,4a,5,6,6a,7,8,9,10,11,12b-dodecahydro-11- hydroxy-4a,7,9,9-tetramethyl-12,13-dioxo-7,11-methano-2H-cycloocta[f][2]benzopyran- 8-acetate, C₃₁H₃₈O₁₁, consists of four six-membered rings (A, B, C and D) and a five-membered furan ring (E). The A ring is fused at C(2)-C(1)-C(10) to the B ring. The B/C and C/D rings are trans- and cis-fused, respectively. Rings A, B, C and D adopt conformations intermediate between twist ²T₄ and boat B_4,1, intermediate between half-chair ¹H₆ and envelope ¹E, distorted chair ¹C₄ and half-chair ⁶H₁, respectively. The crystal structure is stabilized by an intermolecular O-H...O hydrogen bond, three C-H...O intermolecular hydrogen bonds and van der Waals interactions.

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