title: 3-Oxo-18α-olean-28,13β-olide.
abstract: The title terpene, C(30)H(46)O(3), is a 28,13β-lactone of oleanolic acid prepared with bis-muth trifluoro-methane-sulfonate (OTf), Bi(OTf)(3)·xH(2)O. All rings are trans-fused. The X-ray study shows the inversion of the orientation of 18-H in the lactonization reaction. A quantum chemical ab-initio Roothaan Hartree-Fock calculation of the equilibrium geometry of the isolated mol-ecule gives values for bond lengths and valency angles in close agreement with experimental values. The calculation also reproduces the observed mol-ecular conformation, with puckering parameters that agree well with those determined from the crystallographic study.
authors: R C
authors: RC
authors: Santos
authors: R M A
authors: RM
authors: Pinto
authors: A
authors: A
authors: Matos Beja
authors: J A R
authors: JA
authors: Salvador
authors: J A
authors: JA
authors: Paixão
references: J Nat Prod. 2006 May;69(5):807-10
references: 16724846
references: J Nat Prod. 1998 Oct;61(10):1212-5
references: 9784154
references: Biol Pharm Bull. 2007 Jun;30(6):1147-9
references: 17541170
references: J Nat Prod. 2000 Feb;63(2):238-42
references: 10691716
references: Acta Crystallogr D Biol Crystallogr. 2009 Feb;65(Pt 2):148-55
references: 19171970
references: Cancer Lett. 1986 Dec;33(3):279-85
references: 3802058
references: Org Biomol Chem. 2009 Feb 7;7(3):508-17
references: 19156317
references: J Cancer Res Clin Oncol. 1994;120(9):513-8
references: 8045916
references: Nat Rev Drug Discov. 2005 Mar;4(3):206-20
references: 15729362
references: J Nat Prod. 2001 May;64(5):569-71
references: 11374945
references: Cancer Lett. 1995 Aug 1;94(2):213-8
references: 7543366
references: Acta Crystallogr A. 2008 Jan;64(Pt 1):112-22
references: 18156677
references: Nat Prod Rep. 2006 Jun;23(3):394-411
references: 16741586
references: Nat Chem Biol. 2007 Jul;3(7):408-14
references: 17576428