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Nowadays, peptidomimetics are widely studied, being useful tools in drug discovery and medicinal chemistry. The coupling between a carboxylic acid with an amine to form a peptide bond is the most common reaction to obtain peptides/peptidomimetics. In this work, we have investigated an innovative metal‐free photoredox‐catalyzed carbamoylation to form peptidomimetics thanks to the reaction between dihydropyridines functionalized with amino acids (or peptide sequences) and differently functionalized imines. As the organic photocatalyst, we used 4CzIPN, a donor‐acceptor cyanoarene vastly used in photoredox catalysis. By easily modulating the amino acid (or peptide sequence), which is directly attached to the dihydropyridine, we proposed this key‐reaction as new valuable method to obtain peptidomimetics, in situ building the not‐natural portion of the sequence. Moreover, we successfully employed this methodology in solid phase peptide synthesis, both inserting the new photoredox‐generated amino acid at the end or in the middle of the sequence. Peptides with different lengths and secondary structures were prepared, proving the success of this approach, even in sterically hindered environment. Herein, to the best of our knowledge, we describe the first photocatalytic protocol which allows the building of the peptide backbone, with the possibility of simultaneously inserting a non‐coded amino acid in the sequence. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of several chiral (cyclopentadienone)iron complexes (CICs) featuring either two (R)‐BINOL‐derived stereoaxes or a combination of one (R)‐BINOL‐derived stereoaxis and a stereogenic plane. The stereoplane‐containing CICs were obtained as epimer mixtures, which were separated by flash column chromatography and assigned an absolute configuration based on XRD analysis, NMR and order of elution. The library was tested in the asymmetric hydrogenation of ketones showing good catalytic activity and a moderate stereoselectivity which, notably, is mostly imparted by the stereogenic plane. Indeed, the two epimers of each CIC possessing a stereoplane show opposite and equally strong stereochemical preference. [ABSTRACT FROM AUTHOR]

Herein we report a study on the use of donor‐acceptor cyanoarenes as photocatalysts for C−O and C−N coupling reactions promoted by nickel. We found that some of these stable and readily available organic compounds can replace the precious metal photocatalysts originally employed in these methodologies. After reaction optimization, the application scope of the best performing dyes was investigated and found to cover several nucleophiles (alcohols and amines) and aryl bromides. Control experiments, fluorescence quenching studies and examination of yield trends suggest that both etherification and amination probably proceed via a dark NiI/NiIII‐catalytic cycle initiated and sustained by a photoredox cycle involving the organic photocatalysts. [ABSTRACT FROM AUTHOR]

Herein, we investigate the use of organic photocatalysts in the visible light-promoted β-functionalization of carbonyl compounds. In particular, we studied the addition of aliphatic aldehydes to α,β-unsaturated compounds (β-Michael addition), and the reaction of cyclic ketones with either ketones (β-aldol condensation) or imines (β-Mannich reaction). Among the dyes tested, donor-acceptor cyanoarenes gave the best results, promoting the transformations of interest in moderate to good yields. The reaction scope was investigated on substrates with different steric and electronic properties. Fluorescence quenching analysis (Stern-Volmer experiments) led us to propose for these reactions a reductive quenching mechanism involving a transient 5πe - activation mode.