On the ′livingness′ of a dynamic library of cyclophane formaldehyde acetals incorporating calix[4]arene subunits

The acid catalyzed transacetalation of cyclophane formaldehyde acetals incorporating calix[4]arene subunits generates a short-lived dynamic library of macrocycles. The side reaction responsible for the loss of 'livingness' is the unexpected decomposition of monomeric units into a bridged ether and formaldehyde. A plausible mechanism is suggested, in which the crucial step is the formation of benzyl carbocations strongly stabilized by the alkoxy substituents at the lower rim of the calix[4]arene moieties. Copyright (c) 2008 John Wiley & Sons, Ltd.