An aluminum complex based on an amino triphenolate ligand scaffold shows unprecedented high activity (initial TOFs up to 36,000 h(-1)), broad substrate scope, and functional group tolerance in the formation of highly functional organic carbonates prepared from epoxides and CO(2). The developed catalytic protocol is further characterized by low catalyst loadings and relative mild reaction conditions using a cheap, abundant, and nontoxic metal.

Natural peptides show high degrees of specificity in their biological action. However, their therapeutical profile is severely limited by their conformational freedom and metabolic instability. Stapled peptides constitute a solution to these problems and access to these structures lies on a limited number of reactions involving the use of non-natural amino acids. Here, we describe a synthetic strategy for the preparation of unique constrained peptides featuring a covalent bond between tryptophan and phenylalanine or tyrosine residues. The preparation of such peptides is achieved in solution and on solid phase directly from the corresponding sequences having an iodo-aryl amino acid through an intramolecular palladium-catalysed C–H activation process. Moreover, complex topologies arise from the internal stapling of cyclopeptides and double intramolecular arylations within a linear peptide. Finally, as a proof of principle, we report the application to this new stapling method to relevant biologically active compounds.

Al(III) complexes of amino-tris(phenolate) ligand scaffolds have been prepared to attain highly Lewis acidic catalysts. Combination of the aforementioned systems with ammonium halides provides highly active catalysts for the synthesis of organic carbonates through addition of carbon dioxide to oxiranes with initial turnover frequencies among the highest reported to date within the context of cyclic carbonate formation. Density functional theory (DFT) studies combined with kinetic data provides a rational for the relative high activity found for these Al(III) complexes, and the data are consistent with a monometallic mechanism. The activity and versatility of these Al(III) complexes has also been evaluated against some state-of-the-art catalysts and the combined results compare favorably in terms of catalyst construction, stability, activity, and applicability.

Fluorescent antimicrobial peptides are promising structures for in situ, real-time imaging of fungal infection. Here we report a fluorogenic probe to image Aspergillus fumigatus directly in human pulmonary tissue. We have developed a fluorogenic Trp-BODIPY amino acid with a spacer-free C-C linkage between Trp and a BODIPY fluorogen, which shows remarkable fluorescence enhancement in hydrophobic microenvironments. The incorporation of our fluorogenic amino acid in short antimicrobial peptides does not impair their selectivity for fungal cells, and enables rapid and direct fungal imaging without any washing steps. We have optimized the stability of our probes in human samples to perform multi-photon imaging of A. fumigatus in ex vivo human tissue. The incorporation of our unique BODIPY fluorogen in biologically relevant peptides will accelerate the development of novel imaging probes with high sensitivity and specificity.

Multicomponent reactions are excellent tools to generate complex structures with broad chemical diversity and fluorescent properties. Herein we describe the adaptation of the fluorescent BODIPY scaffold to multicomponent reaction chemistry with the synthesis of BODIPY adducts with high fluorescence quantum yields and good cell permeability. From this library we identified one BODIPY derivative (PhagoGreen) as a low-pH sensing fluorescent probe that enabled imaging of phagosomal acidification in activated macrophages. The fluorescence emission of PhagoGreen was proportional to the degree of activation of macrophages and could be specifically blocked by bafilomycin A, an inhibitor of phagosomal acidification. PhagoGreen does not impair the normal functions of macrophages and can be used to image phagocytic macrophages in vivo.