Iteroselectivity: how to control the number of repeated reactions

Our ability to synthetize organic molecules efficiently often revolves around selective reactions. The most commonly studied selectivities are the chemo-, stereo-, and regioselectivities (Figure 1). These selectivities are, however, not sufficient to describe all selective chemical transformations. For instance, when a substrate can undergo the same reaction repeatedly (Figure 2), a new kind of selectivity is needed to obtain one product preferentially. In this context, we conceptualized the “iteroselectivity” that governs the number of repeating chemical transformations that occur on substrates that can undergo at least twice the same reaction.1 Such an iterative process applies to polyfunctional substrates bearing the same type of functional group (e.g. ethylene glycol, sugars, oligomeric macrocycles), and to reactions where the reactive functional group is regenerated (e.g. polymerizations). The different products after each iteration are named iteromers. To achieve high iteroselectivity, it may be necessary to tune the reactivity of the functional groups in a controllable manner. Supramolecular chemistry is a toolbox offering numerous options to modify the reactivity of functional groups by changing their local environment without direct modification of the functional groups in contrast to classical covalent protecting groups. In this communication, we explore examples of iteroselective reactions based on supramolecular protection, supramolecular activation, and templating effects.
info:eu-repo/semantics/published