The water soluble steroid 1 acts as a catalyst for the enolization of the ketones 2 ac. The rate enhancement for 1-catalyzed reaction relative to imidazole-catalyzed reaction (R), increases as the size of the aromatic ring system of the substrate increases; a plot of log R vs π has a slope of 0.43. This is interpreted in terms of hydrophobic binding between steroid α-surface and aromatic ring system which lowers the free energy level of the transition state for ...
[Martinez, Antonio Garcia; Alvarez, Roberto Martinez; Barcina, Jose Osio; Cerero, S. Moya de la; Vilar, E. Teso; et al. Journal of the Chemical Society, Chemical Communications, 1990 , # 22 p. 1571 - 1572]