Phosphorylation of p-tert-butylthiacalix[4]arene: reaction with phosphorous triamides

The reaction of p-tert-butylthiacalix[4]arene 1 with PCl3 gives the phosphorous diester chloride 2 which could be transformed into the double cyclic phosphorous diester amide 3. The conformation of this derivative was found to be 1,2-alternate with two magnetically different phosphorus atoms. The reaction of 1 with P(NEt2)3 gives the asymmetric phosphorus thiacalix[4]arene 4. The conformations of the phosphorus thiacalix[4]arenes 3 and 4 were determined by NMR methods. Phosphorus thiacalixarene 3 was investigated by temperature-dependent 1H NMR and 31P NMR spectroscopy in a range from −80 °C to +120 °C. In this range, no conformational changes could be detected. Due to their different environments, the phosphorus atoms in compound 3 show different reactivities in oxidation experiments with cumene hydroperoxide.