iii) The acid-base control of the host-guest properties enables the recycling of the receptor and, as a consequence, the accumulation of the functionalized product without any loss of selectivity over several cycles; iv) Unstable intermediates bearing two non-compatible reactive groups, such as a primary ammonium bearing an isocyanate group, whose preparation would be highly challenging through classical methods can be stabilized and their reactivity can be controlled through the supramolecular protection of one of their reactive groups; v) Products that are very difficult to access through classical synthetic methods, such as nonsymmetric diamino-diureas, can be readily synthesized in high yield.