A resorcinol derived calix[5]arene with C5-symmetry

1994

Abstract Condensation of 2,4-dihydroxy-3-hydroxymethyl benzophenone (4) in dioxane/H2SO4 gave the cyclic pentamer 5, a calix[5]arene with regular incorporation of the resorcinol units via their 2- and 6-positions. The structure follows from the 1H NMR and mass spectra and was further confirmed by single crystal X-ray analysis. Dynamic NMR in C2D2Cl4 gave a surprisingly high barrier of ΔG‡ = 17.3 kcal/mol for the cone-to-cone ring inversion.