The hydroxide ion catalysed phosphorylation of p-t-butylcalixarene by diethyl chlorophosphate under heterogeneous conditions shows a marked sensitivity to the nature of the phase transfer catalyst used. Thus, substitution of tetraethylammonium bromide for the tetrabutylammonium bromide prescribed for the synthesis of the calixarene tetraphosphate leads to a major reaction product becoming a bis(phosphate) in which the calixarene binds as a unidentate ligand to one phosphorus and as a bidentate ligand to the other. An X-ray crystal structure analysis on this new compound shows the calixarene to adopt a somewhat distorted 'cone' conformation with an unusual orientation of one of the t-butyl substituents into the cone cavity. It also reveals that a significant diastereoselectivity must operate in the formation reaction. The only other reaction product detected in this system appears to be the calixarene tetraphosphate in a partial cone conformation.
|Journal||Australian Journal of Chemistry: an international journal for chemical science|
|Publication status||Published - 1993|
Byrne, L., Harrowfield, J. M., Hockless, D. C. R., Peachey, B. J., Skelton, B., & White, A. (1993). Calixarene Phosphorylation: Cation Control of Reaction Pathways. Australian Journal of Chemistry: an international journal for chemical science, 46, 1673-1683. https://doi.org/10.1071/CH9931673