Synthesis of Bridged, Multifunctional Calixarenes via Ring Closing Metathesis

Ring-closing metathesis catalyzed by RuCl 2 (CHPh)(PCy 3 ) 2 has been used to synthesize calix[4]arenes in cone and 1,3-alternate conformations with upper and lower rim alkenyl bridges. Ester, methoxy, and hydroxy groups have been used to probe the effect of substituents on the mode of metathesis. With some substrates, intermolecular metathesis competes with the intramolecular process leading to oligocalix[4]arenes. X-ray diffraction has been used to reveal the molecular structures of two single-bridged calix[4]arenes and of a double-bridged calix[4]arene.