Source of material: The title compound was prepared by adding an aqueous solution of (L)-(-)-asparagine as the firee base to an aqueous solution of squaric acid in 1:1 molar ratio with continuous stirring of the reactirai mixture during 50 minutes. ТЪе product was purified by repeated crystallization from doubly distilled water. Colorless crystals were grown from an aqueous solution by slow evaporation at room temperature.
The crystal structure of L-(+)-a-bromobenzeneacetic acid (-)-menthyl ester (CI8H25BrO2) is reported. The Br atom and the O(carbonyl) atom are in trans positions.The 1-methyl-4-isopropylcyclohexane ring has a chair conformation. The dihedral angle between the leastsquares plane through the phenyl ring and the leastsquares plane of the C--CO2 group is 45.0 (2) °. The bond distances and angles of the molecule are in the normal ranges.Acta Crystallographica Section C ISSN 0108-2701 01995 TSONKO KOLEV et al.
1635
CommentThe structure determination of the title compound, (I), was undertaken in order to obtain structural information about optically active derivatives of o~-bromobenzeneacetic acid; compounds of this class have not beeninvestigated previously. The data of these compounds are important since optically active c~-bromobenzeneacetic acid is related to the mandelic acids. The latter are basic natural products and play a significant role in stereochemical assignment. SHELXTL-Plus;Sheldrick, 1987) of the title molecule showing the atom-numbering scheme. Anisotropic ellipsoids represent 50% probability boundaries. H atoms are represented as spheres of arbitrary radii.
ExperimentalThe title compound was synthesized by the reaction of (5=)-c~-bromophenylacetyl chloride with (-)-menthol. The (=t=)-c~-bromophenylacetyl chloride was prepared by analogy with the method of the Bristol-Banyu Research Institute The IR spectrum shows a band at 1732 cm -1 in the carbonyl stretching region while the corresponding Raman band is at 1733 cm -1. There is no spectral evidence for the existence of a hydrogen bond between the C==O group and any of the H atoms.
Crystal data1.499 (9) 1.370 (8) 1.38 (1) 1.37 (1) !.36 (1) 1.37 (1)
(5)124.5 (7)
(6)125.0 (6) 104.1 (4)
(5)110.9 (5) 122.4 (6) 119.8 (6) 117.9 (6) 122.2 (6) 119.5 (7) 120.2 (7) 120.3 (7) 120.0 (7) !.52 (l) C(12)--C (13) 1.51 (1)
C( 13)---C(14) 1.54 ( 1 )C (14)---C(15) 1.539 (9) C(15)---C (16) 1.52 (l) C(15)---C(I 7)1.52 (l) O(2)--C(9)--C (14) 106.6 (6) O(2)---C(9)--C (10) 109.9 (6) C(10)---C(9)---C (14) 112.8 (6) C(9)--C(10)--C(I i ) 110.8 (6) C( 10)---C( l i )---C (18) 111.8 (7) C(10)--C(1 l)---C(! 2) li0.1 (7) C(12)---C(! 1)---C (18) 113.1 (7) C(I I)---C(12)---C (! 3) 112.0(6) C(I 2)---C(13)---C (14) 112.3 (6) C(9)---C(14)----C (I 3) 107.1 (6) C(13)---C(14)---C (15) 113.3 (6) C(9)---C(14)---C (15) 113.8 (6) C (14) Data collection: Nicolet R3m/V diffractometer software. Cell refinement: Nicolet R3m/V diffractometer software. Data reduction: Nicolet R3m/V diffractometer software. Program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1987). Program(s) used to refine structure: SHELXTL-Plus and SHELX76 (Sheldrick, 1976). Software used to prepare material for publication: PARST (Nardelli, 1983), PLATON (Spek, 1982) and MISSYM (Le Page, 1987).
One of us (TK) thanks the Alexander von Humboldt Stiftung for a research fellowship.Lists of structure factors, anisotropic displacement parameters, Hatom coordinates and complete geometry have been deposited with the IUC...
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