Recent advancements in supramolecular catalysis are reviewed, which show the potential of related tools when applied to organic synthesis. Such tools are recognized as innovative instruments that can pave the way to alternative synthetic strategies.

An iminopyridine FeIJII) complex, easily prepared in situ by self-assembly of cheap and commercially available\ud starting materials (2-picolylaldehyde, 2-picolylamine, and FeIJOTf)2 in a 2 : 2 : 1 ratio), is shown to be an\ud effective catalyst for the direct hydroxylation of aromatic rings with H2O2 under mild conditions. This catalyst\ud shows a marked preference for aromatic ring hydroxylation over lateral chain oxidation, both in intramolecular\ud and intermolecular competitions, as long as the arene is not too electron poor. The selectivity\ud pattern of the reaction closely matches that of electrophilic aromatic substitutions, with phenol yields and\ud positions dictated by the nature of the ring substituent (electron-donating or electron-withdrawing, orthopara\ud or meta-orienting). The oxidation mechanism has been investigated in detail, and the sum of the accumulated\ud pieces of evidence, ranging from KIE to the use of radical scavengers, from substituent effects\ud on intermolecular and intramolecular selectivity to rearrangement experiments, points to the predominance\ud of a metal-based SEAr pathway, without a significant involvement of free diffusing radical pathways

Predictability is a key requirement to encompass late‐stage C−H functionalization in synthetic routes. However, prediction (and control) of reaction selectivity is usually challenging, especially for complex substrate structures and elusive transformations such as remote C(sp3)−H oxidation, as it requires distinguishing a specific C−H bond from many others with similar reactivity. Developed here is a strategy for predictable, remote C−H oxidation that entails substrate binding to a supramolecular Mn or Fe catalyst followed by elucidation of the conformation of the host‐guest adduct by NMR analysis. These analyses indicate which remote C−H bonds are suitably oriented for the oxidation before carrying out the reaction, enabling prediction of site selectivity. This strategy was applied to late‐stage C(sp3)−H oxidation of amino‐steroids at C15 (or C16) positions, with a selectivity tunable by modification of catalyst chirality and metal.

Time-resolved X-ray absorption (XAS) and UV−vis spectroscopies with millisecond resolution are used simultaneously to investigate oxidation reactions of organic substrates by nonheme iron activated species. In particular, the oxidation processes of arylsulfides and benzyl alcohols by a nonheme iron−oxo complex have been studied. We show for the first time that the pseudo-first-order rate constants of fast bimolecular processes in solution (milliseconds and above) can be determined by time-resolved XAS technique. By following the Fe K-edge energy shift, it is possible to detect the rate of iron oxidation state evolution that matches that of the bimolecular reaction in solution. The kinetic constant values obtained by XAS are in perfect agreement with those obtained by means of the concomitant UV−vis detection. This combined approach has the potential to provide unique insights into reaction mechanisms in the liquid phase that involve changes of the oxidation state of a metal center, and it is particularly useful in complex chemical systems where possible interferences from species present in solution could make it impossible to use other detection techniques.

Substrate-selective C–H oxidation: supramolecular recognition enhances the reactivity of the bound substrate and enables its substrate-selective hydroxylation.

This work aimed to render phenomenologically autonomous the otherwise stepwise operation of a catenane‐based molecular switch, which is chemically triggered by the decarboxylation of 2‐cyano‐2‐phenylpropanoic acid (2). Given that any amount of 2 in stoichiometric excess with respect to the catenane is consumed in a side reaction, the authors resorted to the corresponding anhydride 5, the slow hydrolysis of which, due to adventitious water in dichloromethane, continuously produces in situ the actual fuel 2. As a consequence, the machine does not require a reloading after each cycle, but switches back and forth as long as fuel is present.

In its minimal expression, a supramolecular catalyst that acts on a single bound substrate consists of (i) a binding unit that is complementary to a non‐reacting part of the substrate, (ii) a reactive unit capable of catalyzing the reaction of the bound substrate, and (iii) a spacer connecting the two units in a geometry suitable for productive binding. When binding of two or more species is wanted, the number of binding units increases accordingly. This minireview deals with supramolecular catalysts that use crown ether units for the recognition of one or two reactants involved in a variety of reactions, including cleavage of esters and amides, hydride transfer from dihydropyridine to pyridinium, pyruvate decarboxylation, enolate allylation, radical addition to sodium metacrylate, reduction of NO2– anion to NO, C–H oxidation of aliphatic chains, and Diels‐Alder reactions.

In this work, we propose a method to directly determine the mechanism of the reaction between the nonheme complex Fe II (tris(2-pyridylmethyl)amine) ([Fe II (TPA)(CH 3 CN) 2 ] 2+ ) and peracetic acid (AcOOH) in CH 3 CN, working at room temperature. A multivariate analysis is applied to the time-resolved coupled energy-dispersive X-ray absorption spectroscopy (EDXAS) reaction data, from which a set of spectral and concentration profiles for the reaction key species is derived. These “pure” extracted EDXAS spectra are then quantitatively characterized by full multiple scattering (MS) calculations. As a result, structural information for the elusive reaction intermediates [Fe III (TPA)(κ 2 -OOAc)] 2+ and [Fe IV (TPA)(O)(X)] +/2+ is obtained, and it is suggested that X = AcO – in opposition to X = CH 3 CN. The employed strategy is promising both for the spectroscopic characterization of reaction intermediates that are labile or silent to the conventional spectroscopic techniques, as well as for the mechanistic understanding of complex redox reactions involving organic substrates.