Room-Temperature Practical Copper-Catalyzed Amination of Aryl Iodides

Well-defined nanomagnetic nitrilotriacetic acid complex of Cu(ii) supported on silica-coated nanosized magnetite: a new highly efficient and magnetically separable catalyst for C-N bond formation

A nitrilotriacetic acid (NTA) complex of Cu(ii) supported on silica-coated nanosized magnetite Fe3O4@SiO2-Pr-DEA-[NTA-Cu(ii)]2 was prepared as a new well-defined magnetically separable nanomaterial and fully characterized via IR, XRD, FESEM, TEM, TGA, DLS, BET, VSM, solid-state UV-vis spectroscopy, EDX, ICP-OES, and FESEM-EDX map analyses. Thereafter, it was successfully applied as a new easily magnetically separable and reusable heterogeneous nanocatalyst for the Buchwald-Hartwig C-N bond formation reaction in DMF at 110 °C. Using this method, various kinds of nitrogen heterocycles, such as imidazoles, 2-methyl-1H-imidazole, benzimidazole, indole, and 10H-phenothiazine as well as aliphatic secondary amines such as piperidine, piperazine, morpholine, dimethylamine, and diethylamine, were reacted with aryl halide compounds, and the desired products were obtained with good to excellent yields. In all cases, the applied catalyst could be recovered easily and rapidly using an external magnet and reused 7 times without significant loss of catalytic activity.

Leveraging Ligand Affinity and Properties: Discovery of Novel Benzamide-Type Cereblon Binders for the Design of PROTACs

Immunomodulatory imide drugs (IMiDs) such as thalidomide, pomalidomide, and lenalidomide are the most common cereblon (CRBN) recruiters in proteolysis-targeting chimera (PROTAC) design. However, these CRBN ligands induce the degradation of IMiD neosubstrates and are inherently unstable, degrading hydrolytically under moderate conditions. In this work, we simultaneously optimized physiochemical properties, stability, on-target affinity, and off-target neosubstrate modulation features to develop novel nonphthalimide CRBN binders. These efforts led to the discovery of conformationally locked benzamide-type derivatives that replicate the interactions of the natural CRBN degron, exhibit enhanced chemical stability, and display a favorable selectivity profile in terms of neosubstrate recruitment. The utility of the most potent ligands was demonstrated by their transformation into potent degraders of BRD4 and HDAC6 that outperform previously described reference PROTACs. Together with their significantly decreased neomorphic ligase activity on IKZF1/3 and SALL4, these ligands provide opportunities for the design of highly selective and potent chemically inert proximity-inducing compounds.

Structure-Based Design of Transport-Specific Multitargeted One-Carbon Metabolism Inhibitors in Cytosol and Mitochondria

Multitargeted agents provide tumor selectivity with reduced drug resistance and dose-limiting toxicities. We previously described the multitargeted 6-substituted pyrrolo[3,2-d]pyrimidine antifolate 1 with activity against early- and late-stage pancreatic tumors with limited tumor selectivity. Structure-based design with our human serine hydroxymethyl transferase (SHMT) 2 and glycinamide ribonucleotide formyltransferase (GARFTase) structures, and published X-ray crystal structures of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC), SHMT1, and folate receptor (FR) α and β afforded 11 analogues. Multitargeted inhibition and selective tumor transport were designed by providing promiscuous conformational flexibility in the molecules. Metabolite rescue identified mitochondrial C1 metabolism along with de novo purine biosynthesis as the targeted pathways. We identified analogues with tumor-selective transport via FRs and increased SHMT2, SHMT1, and GARFTase inhibition (28-, 21-, and 11-fold, respectively) compared to 1. These multitargeted agents represent an exciting new structural motif for targeted cancer therapy with substantial advantages of selectivity and potency over clinically used antifolates.

Regioselective Synthesis of Indole-Fused Seven-Membered N-Heterocycles via Photoredox-Catalyzed Intramolecular Cyclization

Herein, we describe the construction of indole-fused seven-membered N- and O-heterocycles from indolyl α-diazocarbonyls via photoredox-catalyzed intramolecular cyclization. The photoredox process features operational simplicity, mild conditions, and as low as 0.1 mol % catalyst loading. The tricyclic heterocycles are obtained in yields of 24 to 67% with excellent regioselectivity. The practicality of this protocol is further demonstrated by gram-scale reactions carried out in both batch and continuous flow.

Adsorption to the surface of hemozoin crystals: Structure-based design and synthesis of new amino-phenoxazine β-hematin inhibitors

In silico adsorption of eight antimalarials that inhibit β-hematin (synthetic hemozoin) formation identified a primary binding site on the (001) face, which accommodates inhibitors via formation of predominantly π-π interactions. A good correlation (r2 = 0.64, P = 0.017) between adsorption energies and the logarithm of β-hematin inhibitory activity was found for this face. Of 53 monocyclic, bicyclic and tricyclic scaffolds, the latter yielded the most favorable adsorption energies. Five new amino-phenoxazine compounds were pursued as β-hematin inhibitors based on adsorption behaviour. The 2-substituted phenoxazines show good to moderate β-hematin inhibitory activity (< 100 μM) and Plasmodium falciparum blood stage activity against the 3D7 strain. N1,N1-diethyl-N4-(10H-phenoxazin-2-yl)pentane-1,4-diamine (P2a) is the most promising hit with IC50 values of 4.7 ± 0.6 and 0.64 ± 0.05 μM, respectively. Adsorption energies are predictive of β-hematin inhibitory activity, and thus the in silico approach is a beneficial tool for structure-based development of new non-quinoline inhibitors.

Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry, i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.

The bibliography includes 350 references.

Synthetic and computational studies on CuI/ligand pair promoted activation of C(Aryl)-Cl bond in C-N coupling reactions

Cu/ligand-mediated coupling reactions have been widely investigated in the recent past. However, activation of cheaper aryl chlorides is still a great limitation of these reactions. During the course of present investigations efforts have been made to develop a normal and facile CuI/ligand pair protocol for arylation of phthalimide using aryl chlorides. The protocol has also been extended for arylation of amines. On the basis of experimental and theoretical results, a catalytic cycle has also been proposed and it has been established that these reactions follow oxidative addition-reductive elimination (OA-RE) pathway. These studies have indicated that tetracoordinated [Cu(L1)(L2)]⁺ complex is active catalytic species in these reactions.

Concise synthesis of N-thiomethyl benzoimidazoles through base-promoted sequential multicomponent assembly

An efficient method for the synthesis of N-thiomethyl benzimidazoles from o-phenylenediamines, thiophenols, and aldehydes via C–N/C–S bond formation under metal-free conditions is described. A broad range of functional groups attached to the substrates were well tolerated in this reaction system. Stable and low-toxicity paraformaldehyde was used as the carbon source.

An efficient method for the synthesis of N-thiomethyl benzimidazoles from o-phenylenediamines, thiophenols, and aldehydes via C–N/C–S bond formation under metal-free conditions is described.

Copper Catalyzed Intramolecular N-Arylation of Ketene Aminals at Room Temperature: Synthesis of 2-Amino-3-cyanoindoles

Various 2-amino-3-cyanoindoles are synthesized through copper catalyzed intramolecular N-arylations of ketene aminals at room temperature for the first time with 60-99% yields within 0.1-2 h. Controlled regioselective N-arylations of unsymmetrical ketene aminals are also studied. Further, a new double heteroannulation approach is demonstrated for the synthesis of 11-aminoindolo[2,3- b]quinolines from acyclic and nonheterocyclic precursors.

Room-Temperature CuI-Catalyzed Amination of Aryl Iodides and Aryl Bromides

A general and effective CuI/N',N'-diaryl-1H-pyrrole-2-carbohydrazide catalyst system was developed for the amination of aryl iodides and bromides at room temperature with good chemoselectivity between -OH and -NH₂ groups. Only 5 mol % of CuI and ligands was needed in this protocol to effect the amination of various aryl bromides and aryl iodides with a wide range of aliphatic and aryl amines (1.3 equiv).

Copper-catalyzed direct alkylation of heteroarenes

An efficient and broadly applicable process is reported for the direct alkylation of C-H bonds in heteroarenes, privileged scaffolds in many areas of science. This reaction is based on the copper-catalyzed addition of alkyl radicals generated from activated secondary and tertiary alkyl bromides to a wide range of arenes, including furans, thiophenes, pyrroles, and their benzo-fused derivatives, as well as coumarins and quinolinones.

Room-temperature Cu-catalyzed N-arylation of aliphatic amines in neat water

A room-temperature copper-catalyzed N-arylation of aliphatic amines with great selectivity and substrate scope tolerance in neat water has been developed.