ISSN:
1572-8854
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract A new naturally occurring sesquiterpene lactone, 3β-acetoxy-8α, 9β-dihydroxy-1αH, 5αH, 6βH, 7αH-guaian-4(15), 10(14), 11(13)-trien-6,12-olide (Scheme 1) has been structurally characterized by X-ray diffraction methods. The compound crystallizes in the monoclinic space groupP21 with two molecules in the unit cell of dimensionsa=8.485(2),b=7.398(1),c=12.919(3) Å,β=98.17(3)°. The structure has been refined to a final value ofR of 0.039 for 2091 observed reflections. The molecule possesses a polyunsaturated guaianolide system which contains a twist chair exomethylenecycloheptane moiety,cis-fused with the exomethylene-cyclopentane [at C(1) and C(5)] andtrans-annelated with theα-exomethylene-γ-lactone at C(6) and C(7). The acetoxy substituent at C(3) isβ-oriented andtrans to the C(8) hydroxyl which, in turn, istrans to the neighboring C(9) hydroxyl. Substitution at C(9) is unprecedented among guaianolides isolated fromCentaureinae subtribe.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01160982
