Easily accessible symmetrically and unsymmetrically bridge disubstituted tetrahydroxycalix[4]arenes in advantageous trans-cone conformation

A new approach to symmetrically and unsymmetrically bridge disubstituted tetrahydroxycalix[4]arenes is reported involving high yields and facile workup of the products. Strong hydrogen bonds at the lower rim force the compounds to adopt the cone conformation with a trans arrangement of the bridge substituents.