Absolute configuration of (2S)-4-(4-hydroxyphenyl)butan-2-ol

The title compound, C10H14O2, was isolated from the chloroform extract of Taxus wallichiana Zucc. In the crystal, molecules are linked by intermolecular O—H⋯O hydrogen bonds, forming sheets parallel to (100). There are weak intermolecular C—H⋯π interactions between the sheets.

The title compound, C 10 H 14 O 2 , was isolated from the chloroform extract of Taxus wallichiana Zucc. In the crystal, molecules are linked by intermolecular O-HÁ Á ÁO hydrogen bonds, forming sheets parallel to (100). There are weak intermolecular C-HÁ Á Á interactions between the sheets.

Comment
The genus Taxus belonging to the family Taxaceae is well known for its anticancer agents, namely taxol and dosetaxel (Wani et al., 1971;Prasain et al., 2001;Nisar et al., 2008a,b;2010). Taxus. wallichiana Zucc. (Himalayan Yew) is a small to medium sized evergreen tree, native to the northern areas of the Pakistan. Literature survey revealed that this plant is used traditionally for the treatment of high fever and acute painful conditions (Kaul, 1997). Leaves of the plant are used to make herbal tea for indigestion and epilepsy (Baquar, 1995;Ahmed, 1997). During our ongoing search on the medicinally important plants of Pakistan, the title compound was isolated from the chloroform-soluble part of Taxus. wallichiana and the structure was established on the basis of X-ray diffraction studies.
The molecular structure of the title compound is shown in Fig. 1. In the crystal structure, molecules are linked by intermolecular O1-H1O1···O2 i and O2-H1O2···O1 ii (see Table 1 for symmetry codes) hydrogen bonds to form two-dimensional sheets paralel to the (100) (Fig.2). A weak C-H···π interaction is also observed. The isolation of 4-(4'-hydroxyphenyl)-(2S)-butanol was previously carried out by Fan et al. (1999). Extraction and purification: The air-dried and powdered bark (4.0 K g) was macerated in methanol with occasional manual shaking at room temperature for a period of 72 h. The process was repeated 3 times followed by filtration. The combined filtrates were evaporated under reduced pressure at 313K to obtain a crude gummy material (514 g, 12.85% w/w), which was suspended in distilled water and successively extracted with hexane (11% w/w), chloroform (31.9% w/w), ethyl acetate (38.8% w/w), and finally with water (18.2% w/w) to give the respective fraction. The chloroform fraction (182 g) was further separated using silica gel column chromatography (95 mm in diameter). The column was eluted with increasing polarities of n-hexane with chloroform (1%-100%) followed by the gradient mixtures of chloroform and methanol. The methanol gradient was increased carefully to collect twenty seven sub-fractions (C1-C27). The sub-fraction C17 (611 mg) obtained on elution with 6% methanol/chloroform mixture was finally purified by flash column chromatography (silica gel, 8 g) by using chloroform: methanol; (95:5) as eluent to yield a colorless crystalline compound, 4-(4'-hydroxyphenyl)-(2S)-butanol (928 mg). Crystals suitable for X-ray diffraction were grown from a solution of the title compound in a mixture of chloroform: methanol (95:5).

Refinement
The hydrogen atoms were located in difference Fourier maps and refined isotropically. The C-H distances refined in the range 0.94 (2)-1.02 (2)Å. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids.

Special details
Experimental Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.