Potassium, calcium, and mixed potassium-calcium amide combinations have been shown to be efficient reagents in enolization reactions, and a set of representative intermediate mono- and heterobimetallic enolates have been successfully isolated and crystallographically characterized.
- inverse crown chemistry
He, X. Y., Noll, B. C., Beatty, A., Mulvey, R. E., & Henderson, K. W. (2004). Ketone deprotonation mediated by mono- and heterobimetallic alkali and alkaline earth metal amide bases: Structural characterization of potassium, calcium, and mixed potassium-calcium enolates. Journal of the American Chemical Society, 126(24), 7444-7445. https://doi.org/10.1021/ja048750m