Synthesis of 1,3- and 1,4-Diacetylamido-Bridged p-tert-Butylcalix[7]arenes

1,3-Oxy-(2ʹ,7ʹ-dioxo-3ʹ,6ʹ-diazaoctamethylene)oxy-bridged p-tert-butylcalix[7]arenes and 1,4-oxy-(2ʹ,8ʹ-dioxo-3ʹ,7ʹ-diazanonamethylene)oxy-bridged p-tertbutylcalix[7]arenes were synthesized regioselectively by a base-promoted alkylation of p-tert-butylcalix[7]arene with dichloro bridging agents [ClCH2CONH(CH2) nNHCOCH2Cl, n = 2, 3], respectively. How­ever, using ClCH2CONH(CH2)6NHCOCH2Cl as a bridging ­reagent, a mixture of 1,3- and 1,4-bridged p-tertbutylcalix[7]arene derivatives were obtained. The bridging pattern and the yields of the products were highly sensitive to the length of bridging reagent and the base employed.