Abstract
C15H18O4 is monoclinic,P21. Unit-cell dimensions at 293 K area=15.048(5),b=9.756(3),c=15.815(5)Å,β=114.18(2)°,V=2118(1)Å3,D x=1.23 g cm−3, andZ=6. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 2816 observed reflections toR=0.054. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The incomptine B occurs as three independent molecules with different conformations. The stereochemistry at C(6), C(7), and C(8) is 6S, 7R, and 8R. The 10-membered ring has an approximate C2 symmetry for the A, B, and C molecules. The α-methylene γ-lactone ring adopts a half-chair conformation for molecule A, and a conformation intermediate betweenβ-envelope and half-chair for the B and C molecules, respectively. The structures are stabilized by a three-dimensional network of O-H⋯O hydrogen bonds and several C-H⋯O interactions.
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Soriano-Garcia, M., Guerrero, C. Structure of (1αH,6βH,7αH,8αH)-1α,10α-epoxy-8β-hydroxy-germacr-2,11(13)-dien-6,12-olide (Incomptine B): A sesquiterpenoid lactone. Journal of Crystallographic and Spectroscopic Research 23, 813–819 (1993). https://doi.org/10.1007/BF01247246
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DOI: https://doi.org/10.1007/BF01247246