Benzhydryl Amines: Synthesis and Their Biological Perspective

Deoxy-Arylation of Amides via a Tandem Hydrosilylation/Radical- Radical Coupling Sequence

Vaska's complex is a prominent catalyst for the hydrosilylation of amides. The O-silyl hemiaminal intermediate formed in these processes has been demonstrated as an electrophile for nucleophilic additions. More recently, these intermediates have been shown to be suitable for single electron reduction to generate α-amino radicals. Leveraging the ability to generate α-amino radicals from these hemiaminals, we describe a two-step, one-pot, deoxy-arylation of amides utilizing iridium-catalyzed hydrosilylation and photoredox catalysis. This transformation can be tailored toward the late-stage functionalization of biologically relevant molecules, with drug discovery applications as shown in the streamlined synthesis of an NPY Y2 inhibitor.

Design, synthesis, and biological evaluation of morpholinopyrimidine derivatives as anti-inflammatory agents

Here, we outline the synthesis of a few 2-methoxy-6-((4-(6-morpholinopyrimidin-4-yl)piperazin-1-yl)(phenyl)methyl)phenol derivatives and assess their anti-inflammatory activity in macrophage cells that have been stimulated by LPS. Among these newly synthesized morpholinopyrimidine derivatives, 2-methoxy-6-((4-methoxyphenyl)(4-(6-morpholinopyrimidin-4-yl)piperazin-1-yl)methyl)phenol (V4) and 2-((4-fluorophenyl)(4-(6-morpholinopyrimidin-4-yl)piperazin-1-yl)methyl)-6-methoxyphenol (V8) are two of the most active compounds which can inhibit the production of NO at non-cytotoxic concentrations. Our findings also showed that compounds V4 and V8 dramatically reduced iNOS and cyclooxygenase mRNA expression (COX-2) in LPS-stimulated RAW 264.7 macrophage cells; western blot analysis showed that the test compounds decreased the amount of iNOS and COX-2 protein expression, hence inhibiting the inflammatory response. We find through molecular docking studies that the chemicals had a strong affinity for the iNOS and COX-2 active sites and formed hydrophobic interactions with them. Therefore, use of these compounds could be suggested as a novel therapeutic strategy for inflammation-associated disorders.

Nickel-Catalyzed Enantioselective Reductive Arylation and Heteroarylation of Aldimines via an Elementary 1,4-Addition

Nickel catalysts of chiral pyrox ligands promoted enantioselective reductive arylation and heteroarylation of aldimines, using directly (hetero)aryl halides and sulfonates. The catalytic arylation can also be conducted with crude aldimines generated from condensation of aldehydes and azaaryl amines. Mechanistically, density functional theory (DFT) calculations and experiments pointed to an elementary step of 1,4-addition of aryl nickel(I) complexes to N-azaaryl aldimines.

Rotational Barriers in N-Benzhydrylformamides: An NMR and DFT Study

N-Benzhydrylformamides are pharmacologically active compounds with anticonvulsant, enzyme-inducing, antihypoxic, and other types of biological activity. The conformational behavior of benzhydrylformamides is determined to a great extent by the presence of substituents at the nitrogen atom and in the ortho-position(s) of the diphenylmethane moiety. Particularly, the NMR spectra of these compounds often contain two sets of signals originating from different orientations of the formyl group. With the use of the dynamic NMR method and DFT calculations, we investigated the internal rotations of aromatic and formyl fragments and estimated the corresponding rotational barriers in N-benzhydrylformamide (BHFA), N-methyl-N-benzhydrylformamide (BHFA-NMe), and in a series of ortho-halogen-substituted N-benzhydrylformamides. It was found that the DFT method at M06-2X/6-311+G* level of theory satisfactorily reproduces the experimental barrier ΔG298≠(Formyl) of the formyl group rotation in BHFA-NMe. In BHFA, BHFA-NMe, and in the ortho-halogen derivatives, the calculated ΔG298≠(Formyl) values are close to each other and lie within 20-23 kcal/mol. On the other hand, the ortho-substituents significantly hinder the rotation of aryl fragment with ΔG298≠(Aryl) values varying from 2.5 kcal/mol in BHFA to 9.8 kcal/mol in ortho-iodo-N-benzhydrylformamide.

New imino-methoxy derivatives: design, synthesis, characterization, antimicrobial activity, DNA interaction and molecular docking studies

Four new diarylmethylamine imine compounds (5a-5d) were prepared in order to examine their DNA binding properties, antimicrobial activity and molecular docking. The compounds were characterized by the common spectroscopic and analytic methods. Furthermore, solid-state structure of compounds 5a and 5c were determined by single-crystal X-ray diffraction studies. The compounds were then investigated for their DNA binding properties employing UV absorption, fluorescence spectroscopy under the physiological pH condition Tris-HCl buffer at pH 7.4. The compounds 5a-5d showed moderate binding constants with Kb values of 3.56 ± 0.3 × 10⁴, 2.18 ± 0.2 × 10⁵, 1.44 ± 0.3 × 10⁵ and 2.56 ± 0.3 × 10⁴ M^-1, respectively. The molecular dockings were performed to investigate the ligand-DNA interactions. The in-silico DNA-compound interaction studies showed that the compounds interact with DNA in groove binding mode. Antimicrobial activity studies of imine compounds were tested against E. coli as bacteria, S. typhimurium, S. aureus, B. cereus, B. subtilis, and C. albicans as fungi. While all compounds show moderate activity against bacteria, no activity against fungi has been investigated.Communicated by Ramaswamy H. Sarma.

Reactivity vs. selectivity of quinone methides: synthesis of pharmaceutically important molecules, toxicity and biological applications

Quinone methides (QMs) are considered to be highly reactive intermediates because of their aromatization both in chemical and biological systems. Being highly accessible, quinone methides (QMs) have been widely exploited and their concurrent use has been manifested for the synthesis of tertiary and quaternary carbon centers of bioactives, drugs and drug-like molecules. In this feature article, the synthetic routes, structure-reactivity relationships and synthetic applications of quinone methides are discussed. Formation of the intermediates during bioactivation of different chemical entities and possible chemical manifestations leading to their toxicity in biological systems are also covered.

Tropylium Salt-Promoted Vinylogous Aza-Michael Addition of Carbamates to para-Quinone Methides: Elaboration to Diastereomerically Pure α,α'-Diarylmethyl Carbamates

Carbocation catalysis is emerging as an important subarea of Lewis acid catalysis. Some stable and isolable carbocations have been successfully utilized as Lewis acid catalysts and promoters in many synthetic transformations. In this manuscript, we report a tropylium cation-promoted vinylogous aza-Michael addition of carbamates to para-quinone methides (QMs) to access a wide range of unsymmetrical α,α'-diarylmethyl carbamates. This mild protocol was effective for the vinylogous conjugate addition of (-)-menthyl carbamate to p-QMs, and the respective diastereomerically pure α,α'-diarylmethyl carbamate derivatives could be obtained in excellent yields and diastereoselectivities (up to >20:1 de).

Atom-efficient transition-metal-free arylation of N,O-acetals using diarylzinc reagents through Zn/Zn cooperativity

Exploiting the cooperative action of Lewis acid Zn(C₆F₅)₂ with diarylzinc reagents, the efficient arylation of N,O-acetals to access diarylmethylamines is reported. Reactions take place under mild reaction conditions without the need for transtion-metal catalysis. Mechanistic investigations have revealed that Zn(C₆F₅)₂ not only acts as a Lewis acid activator, but also enables the regeneration of nucleophilic ZnAr₂ species, allowing a limiting 50 mol% to be employed.

Operating via a special type of Zn/Zn′ cooperation, a new transition-metal free and atom efficient method of arylating N,O-acetals has been developed combining nucleophilic ZnPh₂ with Lewis acidic Zn(C₆F₅)₂.

Silver-Catalyzed N-H Functionalization of Aryl/Aryl Diazoalkanes with Anilines

Herein, we report on the N-H functionalization reaction of primary and secondary anilines with diaryldiazoalkanes using simple AgPF₆ as catalyst. We demonstrated broad applicability in the reaction of diaryldiazoalkanes with different anilines (31 examples, up to 97% yield). Furthermore, we propose a possible reaction mechanism for the N-H functionalization.

Synthesis and Biological Evaluation of Novel Benzhydrylpiperazine-Coupled Nitrobenzenesulfonamide Hybrids

A series of novel benzhydryl piperazine-coupled nitrobenzenesulfonamide hybrids were synthesized with good to excellent yields. They were tested for in vitro inhibition of mycobacterial activity against the Mycobacterium tuberculosis H37Rv strain, in vitro cytotoxicity MTT (RAW 264.7cells) assay, nutrient starvation (H37Rv strain), and ability to block Cav3.2 T-type calcium channels. Novel hybrids did not inhibit T-type calcium channels, whereas they showed excellent antituberculosis (TB) activity and low cytotoxicity with a selectivity index of >30. A direct impact of the amino acid linker was not observed. Studied hybrids exhibited good inhibition activities, and the 2,4-dinitrobenzenesulfonamide group emerged as a promising scaffold for further drug design by hybridization approaches for anti-TB therapy.