A multicomponent reaction towards N-(cyanomethyl)amides

Nitrile-based peptoids as cysteine protease inhibitors

Peptidomimetics of the class of dipeptidyl nitrile analog peptoids were synthesized as inhibitors of mammalian cysteine proteases of the papain superfamily. The dipeptidyl nitrile side chains were attached to the peptide backbone's nitrogen atom, not to the α-carbons. Synthesized nitrile-based peptoid analogs that lack the hydrogen amide at P2-P3 are responsible for many of the secondary structure elements in peptides and proteins, making them resistant to proteolysis. The designed peptoids would lose a hydrogen bond with cruzain Asp161 decreasing the affinity toward the enzyme. A structure-activity relationship and matched molecular pair-based analysis between the dipeptidyl nitrile Neq0409 and its peptoid 4a yielded the following cruzain affinities: pK_i^Neq0409 = 6.5 and pK_i^4a = 5.2. respectively. A retrosynthetic matched molecular pair cliff (RMMP-cliff) analysis with a ΔpK_i^Neq0409-4a of 1.3 log is found for this transformation. These novel peptoids were then optimized, leading to compound 4i, with high cruzain inhibition (pKi = 6.8). Cross-class cathepsin activity was observed for some of these novel compounds against cathepsins K, L and S, while other compounds presented a selective inhibition of cathepsin K (4b, 4c, 4k) over ten times higher than the other enzymes. The putative mode of binding was determined by using covalent docking, which also aided to describe the structure-activity relationship (SAR). Interestingly, none of the peptoids inhibited CatB to any appreciable extent. These results provide guidance to identify novel bioactive nitrile-based peptoids.

To each his own: isonitriles for all flavors. Functionalized isocyanides as valuable tools in organic synthesis

The term functionalized isocyanides refers to all those isocyanides in which a neighbouring functional group can finely tune the reactivity of the isocyano group or can be exploited in post-functionalization processes. In this manuscript, we have reviewed all the isocyanides in which the pendant functional group causes either deviation from or reinforces the normal reactivity of the isocyano group and categorized them to highlight their common features and differences. An analysis of their synthetic potential and the possible unexplored directions for future research studies is also addressed.

A triple-functionalised metal centre-catalyzed enantioselective multicomponent reaction

A model of a triple-functionalised metal centre for the discovery of unprecedented enantioselective reactions was exquisitely developed by using a Rh^I/(DHQ)₂PHAL catalyst system via multiple coordination interactions with different ligands and substrates.

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

Aziridine aldehyde dimers, peptides, and isocyanides participate in a multicomponent reaction to yield peptide macrocycles. We have investigated the selectivity and kinetics of this process and performed a detailed analysis of its chemoselectivity. While the reactants encompass all of the elements of the traditional Ugi four-component condensation, there is a significant deviation from the previously proposed mechanism. Our results provide evidence for an imidoanhydride pathway in peptide macrocyclization and lend justification for the diastereoselectivity and high effective molarity observed in the reaction.

A microwave-assisted diastereoselective multicomponent reaction to access dibenzo[c,e]azepinones: synthesis and biological evaluation

An unprecedented microwave-assisted multicomponent strategy has been elaborated for the fast, efficient, and diastereoselective generation of the dibenzo[c,e]azepinone scaffold. The generated compounds were evaluated for their bioactivity.

Direct Dynamic Protein-Affinity Selection Mass-Spectrometry

A new methodology is described enabling the affinity screening of potential ligands towards the human estrogen receptor alpha ligand binding domain (ERα-LBD). In-solution incubation is performed of the analyte and the His-tagged ERα-LBD. The bound complex is immobilized on a nickel-loaded protein-affinity selection column, where after the unbound fraction is removed. The immobilized protein–ligand complex is exposed to a decreased pH value and an increased organic modifier concentration releasing the ligand for MS detection, and precipitating the proteins on a filter positioned between the affinity column and the mass spectrometer. The trapping column can be regenerated for reuse at least 70 times. The advantages of the methodology over existing methodologies are the absence of a pre-concentration as well as a chromatographic separation step, resulting in a significantly shorter analysis time compared to previously described procedures, and in addition, allowing the determination of solutes with unfavorable chromatographic properties. The overall analysis time now can be reduced about 250% to approximately 6 min. Replacing the filters after every measurement results in an intra-day standard deviation of 14.8% and an inter-day standard deviation of 21.3%.