Synthesis and Core and Surface Reactivity of Phosphorus‐Based Dendrons

Abstract

Abstract A series of phosphorus‐containing dendrons is synthesized starting from a unique precursor (EtO) 2 P(O)CH=CHC 6 H 4 PPh 2 ( 3‐G 0 ), whose X‐ray crystal structure shows an extended planarity between both phosphorus. Staudinger reactions with functionalized azides on the phosphino group are the first step for the growth of the dendrons, which is continued using a divergent method. Several types of reactions are performed on dendrons of several sizes, either at the level of the core or of the surface. The specific addition of methyl triflate to P=S and trimethylsilyl triflate to P=O at the level of the core affords a dicationic species. A 13 C NMR spectroscopic study indicates to what extent the charges are delocalized. Phosphanes are grafted on the surface of a second‐generation dendron, and used for the complexation of PdCl 2 . Both compounds possess five different types of phosphorus atoms, which helps in characterizing them by 31 P NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)