Bis- and tetracalix[4]arenes in the partial cone conformation: synthesis, structure and RCM reactions

The synthesis, structure and ring-closing metathesis (RCM) reactions of polyether bridged biscalix[4]arenes in the partial cone conformation with upper rim allyl substituents are reported. The RCM reaction modes depend on the length of polyether chain. Diethylene glycolic chain produced the dimer and linear oligomer with multi-cavities, whereas triethylene and tetraethylene glycolic chains allowed direct cyclization through intramolecular head-to-tail pattern to yield novel bridged biscalix[4]arenes .