Dioxamethylene intramolecular bridging of p-tert-butylcalix[8]arene

The first examples of dioxamethylene bridged calix[8]arenes 2-6 have been obtained by Cs2CO3-promoted direct O-alkylation of p-tert-butylcalix[8]arene with BrCH2Cl. Assignment of the 1,2-, 1,2:3,4-, 1,2:3,4:6,7-, 1,4:2,3:5,6:7,8-, and 1,2:3,4:5,6:7,8-bridging pattern of 2-6, respectively, was mainly based on chemical shift of OH groups and chemical correlations. Dynamic H-1 NMR studies and MM3 calculations indicated that in these compounds the dioxocine subunit adopts a boat-chair conformatio