Acta Crystallographica Section C

Crystal Structure Communications

Volume 60, Part 6 (June 2004)

fr1475 scheme

Acta Cryst. (2004). C60, o408-o410 [doi:10.1107/S010827010400839X]

(-)-Parasantonic acid and its enol lactone, (+)-parasantonide: observation of the rare acid-to-acid catemeric hydrogen-bonding mode in a ,-diketocarboxylic acid

J. Zinczuk, E. A. Ruveda, H. W. Thompson and R. A. Lalancette

Abstract: The title diketo acid, (-)- $\alpha$ ,3a,7-trimethyl-5,8-dioxo-1,4-ethanoperhydropentalene-1-acetic acid, C $_{15}$ H $_{20}$ O $_{4}$ , is shown to aggregate in the solid state as acid-to-acid hydrogen-bonded catemers, whose chains follow 2 screw axes from each carboxyl H atom to the C=O group of a neighboring carboxyl group [OO = 2.672 (4) Å and OH-O = 173°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonded chains pass through the cell in the a direction. Two intermolecular C=OH-C close contacts are present in this compound. Both this diketo acid and its enol lactone, (+)-parasantonide [systematic name: (-)- $\alpha$ ,3a,7-trimethyl-5-oxo-1,4-ethenoperhydropentalene-1,8-carbolactone], C $_{15}$ H $_{18}$ O $_{3}$ , have an R configuration at the methylated chiral center adjacent to the carboxyl group, unlike the precursor from which they are derived, viz. (-)-santonic acid.

Formula: C₁₅H₂₀O₄ and C₁₅H₁₈O₃

Online 11 May 2004


	Structure factor file (CIF format) (70.3 kbytes) Contains datablock I

	Structure factor file (CIF format) (71.4 kbytes) Contains datablock II

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