Synthesis, structure, and reactivity of tetrakis(O,O-phosphorus)-bridged calix[4]resorcinols and their derivatives

The synthesis and characterisation of the reactive tetrakis(O,O-phosphorus)-bridged calix[8]resorcinols 3 and 4 is described. Because of its poor solubility in common organic solvents, a solid-state NMR investigation of 3 (H-1, C-13, P-31) was conducted. Reaction of 3 with MeMgI, Me3SiNMe2, and HNMe2 furnished the sigma(3) lambda(3)P-substituted cavitands 5 and 6. Oxidative addition reactions of 6 with the (H2N)(2)C(=O)/H2O2 (1:1) adduct, tetrachloro-o-benzoquinone (TOB), and hexafluoroacetone (HFA) led to the sigma(4) lambda(5)P derivative 7, and to the sigma(5) lambda(5)P derivatives 8 and 9. An X-ray crystal-structure determination of the tetrakis(O,O-phosphorus)-bridged calix[4]resorcinol 4 has been conducted. The framework displays the cone conformation; the chlorine atoms are directed inwards.