Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807032503/ez2086sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807032503/ez2086Isup2.hkl |
CCDC reference: 657724
Acetic anhydride (30 mol equivalents) was added dropwise to a stirred solution of (S)-(+)-Leucine (1 mol equivalent) in formic acid (approximately 30 ml per 1.0 g of amino acid) at 0°C. After addition of the acetic anhydride, the external ice bath was removed and the solution stirred at room temperature for 24 h. The solution was treated with water (60 ml) and stirred for 1 hr. The solvent was removed under reduced pressure to yield a white residue. This residue was recrystallized from water to yield the pure product (I) (Boyle et al., 2004). Yield 72%. Colorless crystals suitable for X-ray diffraction were obtained by evaporation of water at room temperature in a fume hood over a period of 2 days.
Hydrogen atoms were first located in the difference map then positioned geometrically and allowed to ride on their respective parent atoms, with C—H = 0.93 or 0.97 Å, N—H = 0.86 Å and O—H = 0.82 Å. Uiso(H) values were set equal to 1.5Ueq for methyl C and O and 1.2Ueq for the remainder.
The title compound (I) was synthesized as an intermediate in the synthesis of a chiral secondary alcohol. This chiral alcohol was in turn used as a chiral source in ligands used for the asymmetric addition of diethylzinc to benzaldehyde (Boyle et al., 2004).
The title compound was synthesized from commercial (S)-(+)-leucine and the stereochemistry is retained during the reaction. The structure therefore contains only a single enantiomer. The unit cell contains a single molecule. C6 and N1 are equatorial to the plane through C1 and C5 along the backbone of the molecule. Fig. 1 illustrates the geometry of the molecule and the labelling scheme employed. Each molecule exhibits intermolecular hydrogen bonding (N1—H1···O2i and O1—H1A···O3ii), resulting in a layered structure with O—H···O hydrogen bonding interactions between molecules within the layer and N—H···O interactions between layers. The molecular packing and hydrogen bonding interactions are shown in Fig. 2.
For related literature, see: Boyle et al. (2004).
The title compound (I) was synthesized as an intermediate in the synthesis of a chiral secondary alcohol. This chiral alcohol was in turn used as a chiral source in ligands used for the asymmetric addition of diethylzinc to benzaldehyde (Boyle et al., 2004).
The title compound was synthesized from commercial (S)-(+)-leucine and the stereochemistry is retained during the reaction. The structure therefore contains only a single enantiomer. The unit cell contains a single molecule. C6 and N1 are equatorial to the plane through C1 and C5 along the backbone of the molecule. Fig. 1 illustrates the geometry of the molecule and the labelling scheme employed. Each molecule exhibits intermolecular hydrogen bonding (N1—H1···O2i and O1—H1A···O3ii), resulting in a layered structure with O—H···O hydrogen bonding interactions between molecules within the layer and N—H···O interactions between layers. The molecular packing and hydrogen bonding interactions are shown in Fig. 2.