Synthesis and configurational analysis of mixed-bridged phosphate cavitands

Mixed-bridged cavitands derived from tetramethyl-resorcinarene having respectively, methylene, ethylene and p-tolyl phosphate bridging groups are synthesized. The in-out isomers of each cavitand are separated and characterized. The diastereoselectivity in favour of the in isomer in the phosphate bridging reaction is determined by the nature of the bridging units already present on the macrocycle. The X-ray crystal structure of a fourfold-bridged phosphate cavitand in the ioio configuration reveals the spatial disposition of the phosphate bridges with:, the convergence of two P = O groups toward the centre of the cavity.