Isolation and crystal structure of lawinal

The structure of the natural product lawinal [systematic name: (-)-(2S)-5,7-dihydroxy-6-methyl-4-oxo-2-phenylchromane-8-carbaldehyde, C17H14O5] at 150K is reported. The compound crystallizes with monoclinic (I2) symmetry and with Z′ = 2. The absolute configuration could not be determined reliably from X-ray analysis only. However, our analysis returns the S-configuration at the C-2 position, consistent with previous stereochemical assignment from specific rotation. The independent molecules form into alternating hydrogen-bonded chains with C - H⋯O=CH intermolecular linkages that run parallel to the crystallographic a axis and are extended into the ac plane by π-π interactions between their phenyl substituents.