Cyclophosphazenic polypodands as powerful cation complexing agents, efficient phase-transfer catalysts and anion activators

A survey dealing with cyclophosphazenic polypodands 3a-c, a new class of ''octopus-like'' molecules is reported. These many-armed ligands are powerful complexing agents of alkali metal salts and hence behave as very efficient catalysts in many reactions (nucleophilic substitutions, eliminations, alkylations, oxidations, reductions) under solid-liquid and liquid-liquid phase-transfer catalysis conditions. Their catalytic activity is much better than that of the open-chain analogues PEGs 4, 5 and TRIDENT-1, 6. Moreover, anion activation realized by cyclophosphazenic polypodands, both in homogeneous and heterogeneous systems, is comparable with that obtained with the more sophisticated and expensive crown ethers.