sp-(R)-9-(o-tert-Butylphenyl)-9-hydroxy-N-[(S)-α-methylbenzyl]fluorene-2-carboxamide–Acetone: a Novel 1:1 Cavitate

Fractional crystallization of the two epimers sp-(R),(S)-9-(o-tert-butylphenyl)-9-hydroxy-N-[(S)-1-phenylethyl]fluorene-2-carboxamide from acetone provided the title epimer as a 1:1 cavitate (C₃₂H₃₁NO₂.C₃H₆O) with the solvent acetone. Hydrogen bonding between NH group of the host molecule and the O atom of a molecule of acetone takes place within a cavity of the host molecule, forming the novel cavitate. In addition, molecules of the host are connected to one another through hydrogen bonds between their respective OH groups as donors and amide O atoms as acceptors, forming molecular chains. To accommodate the molecule of acetone and its hydrogen bonding within the cavity, the o-tert-butylphenyl group of the title host, in contrast to that in its parent sp-9-(o-tert-butylphenyl)-9-fluorenol, is substantially rotated away from perpendicularity with the fluorene plane.

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