title: Absolute configuration of vouaca-pen-5α-ol.
abstract: The title compound, C(20)H(30)O(2), {systematic name: (4aR,6aS,7R,11aS,11bR)-4,4,7,11b-tetra-methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca-hydro-phenanthro[3,2-b]furan-4a-ol}, is a cas-sane furan-oditerpene which was isolated from the roots of Caesalpinia pulcherrima. The absolute configurations at positions 4a, 6a, 7, 11a and 11b are R, S, R, S and R, respectively. The mol-ecule has four-fused rings consisting of three cyclo-hexane rings and one furan ring. The three cyclo-hexane rings are trans-fused. Two cyclo-hexane rings are in chair conformations, while the third is in an envelope conformation. In the crystal structure, the mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds into a zigzag chain along the a axis. A short O⋯O contact [3.0398 (14) Å] is also present.
authors: Hoong-Kun
authors: HK
authors: Fun
authors: Orapun
authors: O
authors: Yodsaoue
authors: Suchada
authors: S
authors: Chantrapromma
authors: Chatchanok
authors: C
authors: Karalai
references: Acta Crystallogr Sect E Struct Rep Online. 2010 Jul 17;66(Pt 8):o2059-60
references: 21588364
references: Planta Med. 2003 Aug;69(8):776-7
references: 14531033
references: J Nat Prod. 2002 Aug;65(8):1107-10
references: 12193012
references: Acta Crystallogr D Biol Crystallogr. 2009 Feb;65(Pt 2):148-55
references: 19171970
references: J Nat Prod. 2001 Oct;64(10):1266-72
references: 11678648
references: J Nat Prod. 1986 Jul-Aug;49(4):561-9
references: 3783154
references: Acta Crystallogr A. 2008 Jan;64(Pt 1):112-22
references: 18156677