Acta Crystallographica Section C

Crystal Structure Communications

Volume 61, Part 4 (April 2005)

organic compounds

gg1241 scheme

Acta Cryst. (2005). C61, o249-o252 [doi:10.1107/S0108270105004944]

Two (+)-,4-dimethyl-2-oxocyclohexaneacetic acids: hydrogen bonding in a terpenoid -keto acid and in a diastereomeric lactol

M. Davison, E. M. Kikolski, D. Mostafavi, R. A. Lalancette and H. W. Thompson

Abstract: The (+)-( [alpha] S,1S,4R)-diastereomer of the title structure, C₁₀H₁₆O₃, aggregates in the solid as non-symmetric dimers with disorder in both carboxyl groups [OO = 2.710 (5) and 2.638 (5) Å]. The two molecules constituting the asymmetric unit pair around a pseudo-twofold rotational axis and differ only slightly in their distances and angles, but one methyl group displays rotational disorder absent in the other molecule. Five intermolecular C-HO close contacts exist, involving both ketone groups. The (+)-( [alpha] R,1R,4R)-diastereomer exists in the crystal in its closed-ring lactol form, (3R,3aR,6R,7aR)-2,3,3a,4,5,6,7,7a-octahydro-7a-hydroxy-3,6-dimethylbenzo[b]furan-2-one, C₁₀H₁₆O₃, and aggregates as hydrogen-bonded catemers that extend from the hydroxyl group of one molecule to the carbonyl group of a neighbor screw-related along b [OO = 2.830 (3) Å and O-HO = 169°]. One close intermolecular C-HO contact exists involving the carbonyl group.

Formula: Two forms of C₁₀H₁₆O₃


	Structure factor file (CIF format) (106.3 kbytes) Contains datablock I

	Structure factor file (CIF format) (52.0 kbytes) Contains datablock II

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