| Popis: |
The lactone ring of the guaianolide-class sesquiterpene lactone [3S-(3α,3aα,9α,9aα,9bβ)]-3a,4,5,7,8,9,9a,9b-octahydro-9-hydroxy-3,6,9-trimethylazuleno[4,5-b]furan-2(3H)-one, C 15 H 22 O 3 , is trans-fused to the seven-membered ring. Two molecules are present in the asymmetric unit ; they differ only slightly in conformation. The seven-membered ring is in the chair conformation, with the local mirror bisecting the double bond. The lactone is in the envelope conformation, while the other five-membered ring adopts the half chair. The two independent molecules form a hydrogen-bonded dimer, with O...O distances 2.907 (3) and 2.966 (2) A. |
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