The crystal structure of hop-17(21)-en-3β-yl acetate of Pluchea pteropoda Hemsl. from Vietnam

C32H52O2 (293K). monoclinic space group C2, a= 13.227(7), b= 6.600(1), c= 32.514(2) Angstrom, beta=96.18(5)degrees, V= 2821.9(16) Angstrom(3), D-x = 1.103 g.cm(-3), Z= 4, F(000)= 1040, lambda(CuK alpha)=1.5418 Angstrom, mu= 0.499 mm(-1). The title compound isolated from the roots of a Vietnamese plant and being known for its activity against fever was identified by this X-ray analysis to be a pentacyclic triterpene of hopanoide type with a C17=C21 endocyclic-double bond in the five membered ring. The presence of several axially substituted methyl groups on both the alpha and beta side causes the so called "mid-molecule strain" having already been reported in the literature for other hopane type ring systems.