Highly distorted Cone calix[4]arenes through intramolecular mc murry coupling reaction

Highly distorted and rigid cone conformers of calix[4]arene have been synthesized by low-valent titanium promoted intra-molecular coupling of aldehydes 1a-d. The reaction outcome strongly depends on the substituents present at the upper rim and reaction time. In all cases examined infra-molecular coupled compounds, having a bridge only two atoms long, were obtained in about 30% yield. © 1995 Elsevier Science Ltd