(±)‐7‐Oxo‐1,2,3,4,4a,5,6,7‐octahydronaphthalene‐1‐acetic acid: catemeric hydrogen bonding and diastereomeric disorder in a bicyclic unsaturated ɛ‐keto acid |
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Authors: | Mark Davison Hugh W Thompson Roger A Lalancette |
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Abstract: | The 68.5:31.5 mixture of diastereoisomers obtained in the synthesis of the title compound, C12H16O3, yielded sharply melting crystals containing the same ratio of epimers, in a disordered crystallographic arrangement. The disorder resides almost entirely in the carboxymethyl side chain, but places the two sets of carboxyl O atoms at nearly identical paired spatial positions. Neither component displays significant carboxyl disorder, and the molecules aggregate as hydrogen‐bonded carboxyl‐to‐ketone catemers O⋯O = 2.673 (4) Å and O—H⋯O = 158°] having glide‐related components, with centrosymmetrically related pairs of chains following axes perpendicular to b. Close intermolecular C—H⋯O contacts exist for both the ketone and the carboxyl group. The energetics of the epimers and of their crystallization mode are discussed. |
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