Ipso-Nitration of p-tert-Butylcalix[4]arenes with tert-Butyl Nitrite

Abstract

In order to develop new ipso-nitration reagents, tert-butyl nitrite has been used to ipso-nitrate a variety of p-tert-butylcalix[4]arene derivatives. The nitration experiments showed that the ipso-nitration with tert-butyl nitrite can be executed in moderate-to-high yields (up to 95%). The optimal reaction solvent, temperature, time, and tert-butyl nitrite amount for ipso-nitration of 1a are 1,2-dichloroethane, 80 °C, 24 h, and 20 equiv., respectively. The p-tert-butylphenoxy unit carrying an electron-donating substituent can undergo ipso-nitration, and that carrying an electron-withdrawing substituent can't. Calix[4]arene conformation can affect the ipso-nitration rate, but can't determine whether the ipso-nitration takes place or not. The nitration results confirm that tert-butyl nitrite can be used as an alternative and efficient reagent for the ipso-nitration of p-tert-butylcalix[4]arene derivatives.