6α-Hy­droxy-5,6-dihydro­salviasperanol

Safra Izuani Jama Asik; Ibrahim Abdul Razak; Abdul Wahab Salae; Suchada Chantrapromma; Hoong-Kun Fun

doi:10.1107/S160053681004208X

. 2010 Oct 23;66(Pt 11):o2899. doi: 10.1107/S160053681004208X

6α-Hydroxy-5,6-dihydrosalviasperanol

Safra Izuani Jama Asik ^a, Ibrahim Abdul Razak ^a, Abdul Wahab Salae ^b, Suchada Chantrapromma ^b,^‡, Hoong-Kun Fun ^a,^*,^§

PMCID: PMC3009237 PMID: 21589076

Abstract

In the title compound, C₂₀H₂₈O₄, a diterpenoid isolated from the roots of Premna obtusifolia (Verbenaceae), the five-membered ring is in a half-chair conformation. One six-membered ring exists in a twisted-boat conformation while the other is in half-boat conformation. The crystal packing is stabilized by intermolecular O—H⋯O and weak C—H⋯O interactions, generating (001) sheets.

Related literature

For background to Verbenaceae, diterpenes and their biological activity, see: Hymavathi et al. (2009 ▶); Bunluepuech & Tewtrakul (2009 ▶); Esquivel et al. (1995 ▶). For ring conformations and ring puckering analysis, see: Cremer & Pople (1975 ▶). For bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₀H₂₈O₄
M _r = 332.42
Orthorhombic,
a = 6.2767 (2) Å
b = 11.7358 (4) Å
c = 23.7496 (7) Å
V = 1749.45 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.49 × 0.36 × 0.24 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005) T _min = 0.959, T _max = 0.979
15028 measured reflections
3534 independent reflections
3079 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.107
S = 1.15
3534 reflections
233 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681004208X/hb5689sup1.cif

e-66-o2899-sup1.cif^{(22.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681004208X/hb5689Isup2.hkl

e-66-o2899-Isup2.hkl^{(173.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1O3⋯O2ⁱ	0.85 (3)	2.01 (3)	2.8504 (17)	169 (3)
O4—H1O4⋯O1ⁱⁱ	0.84 (3)	1.89 (3)	2.7089 (16)	165 (3)
C18—H18B⋯O3ⁱⁱⁱ	0.96	2.55	3.407 (2)	149

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

SIJA, IAR and HKF thank Universiti Sains Malaysia for the Research University Grant (No.1001/PFIZIK/811151). SC thanks the Prince of Songkla University for generous support through the Crystal Materials Research Unit.

supplementary crystallographic information

Comment

Plants of the family Verbenaceae were found to possess interesting biological properties such as cytotoxicity (Hymavathi et al., 2009) and anti-HIV-1 integrase activities (Bunluepuech & Tewtrakul, 2009). The phytochemistry study of the aerial parts of Premna obtusifolia (Verbenaceae), a small tree found in the mangrove forests which were collected from Satun province in the southern part of Thailand, led to the isolation of diterpenes. The title compound which is known as 5,6-dihydro-6α-hydroxysalviasperanol (Esquivel et al., 1995) is one of the isolated compounds from this plant. Herein we report the crystal structure of the title compound (I).

The bond lengths show normal values (Allen et al., 1987). The pyrocatechol, C8/C9/C11–C14/O3/O4, is planar with the maximum deviation of 0.006Å for atom C12. The five-membered ring, C5–C7/C10/O1, is in half-chair conformation with the puckering parameter Q = 0.4588 (16)Å, φ = 194.0 (2)°. The six-membered ring, C1–C5/C10 adopts twisted-boat conformation with puckering parameter Q = 0.6536 (18)Å, θ = 79.56 (16)° and φ = 156.60 (16)°. The other six-membered ring , C7–C10/C20/O1, is in half-boat conformation with puckering parameter Q = 0.5929 (15)Å, θ = 47.83 (15)° and φ = 347.9 (2)° (Cremer & Pople 1975). The torsion angles of propanyl group attached to the pyrocatechol ring are C14–C13–C15–C17 = -101.80 (19)° and C14–C13–C15–C16 = 78.55 (19)°.

The crystal packing of (I) is stabilized by intermolecular O3—H1O3···O2 and O4—H1O4···O1 and weak C18—H18B···O3 interactions. The molecules are linked into infinite two dimensional networks parallel to ab plane.

Experimental

The air-dried roots of Premna obtusifolia (4.5 kg) were extracted with CH₂Cl₂ (2 x 20 L) under room temperature. The combined extracts were concentrated under reduced pressure to give a dark yellow extract (40.5g) which was subjected to quick column chromatography (QCC) over silicagel using solvents of increasing polarity from n–hexane to EtOAc to afford 12 fractions (F1–F12). Fraction F10 was further purified by QCC using CH₂Cl₂–EtOAc (3:7), yielding compound (I) (145.8 mg). Colorless block-shaped single crystals of (I) were recrystallized from CH₂Cl₂ after several days (m.p.461–463 K).