Catalytic activity of cyclophosphazenic polypodands in phase-transfer reactions. Comparison with open-chain analogues

Article abstract of DOI:10.1016/S0040-4020(01)89750-7

The catalytic activity of cyclophosphazenic polypodands 1a-c was evaluated in typical reactions performed under solid-liquid (SL) and liquid-liquid (LL) phase-transfer catalysis (PTC) conditions. Such activity is largely determined by the complexation extent of 1a-c which is in turn related to the number of binding sites of the ligand (1a<1b≤1c) and to the nature of the inorganic salt M⁺Y^- (Na⁺>K⁺2>Rb⁺ and SCN^- I^-> Br^-). Also the presence of water was found to play an important role. Comparison with open-chainanalogues PEG 2 and TRIDENT 3 showed that polypodands 1a-c due to their excellent stability simplicity of preparation and high complexing ability can be considered promising phase transfer catalysts especially under SL-PTC conditions. Cyclophosphazenic polypodands are efficient catalysts in anion promoted reactions (e.g. nucleophilic substitution, alkylation, reduction, oxidation reactions) under SL and LL-PTC conditions. Catalytic activity is mainly related to their complexation capability.