Molecular and crystal structures of 1R,4S-2-(4-carbomethoxy)benzylidene-n-menthan-3-one

The molecular and crystal structures of chiral 1R,4S-2-(4-carbomethoxy)benz ylidene-n-menthan-3-one (I) are determined by X-ray diffraction analysis. C rystals I are orthorhombic; at 20 degreesC: a = 11.961(3) Angstrom, b = 26. 453(8) Angstrom, c = 5.400(2) Angstrom, space group P2(1)2(1)2(1), and Z = 4(C19H25O3). In molecule I, the cyclohexanone ring with the axial methyl an d isopropyl substituents adopts a chair conformation. It is found that the enone and arylidene fragments of compound I have a substantially nonplanar structure. The shortened intramolecular contacts between atoms of the aryli dene grouping and the oc fragment of the cyclohexanone ring and their assoc iated distortions of bond angles at the sp(2) carbon atoms are the common s tructural features of 2-arylidene-n-menthan-3-ones irrespective of the ster eochemical configuration of the C(4) chiral center. (C) 2001 MAIK "Nauka/In terperiodica".