Strategic Advances in Sequential C-Arylations of Heteroarenes

Sequence-specific C-arylation strategies have important applications in medicinal and material research. These strategies allow C-C bond formations in a regioselective manner to synthesize large molecular libraries for studying structure-activity profiles. The past decade has seen the development of single C-C bond forming reactions using various transition-metal catalysts, cryogenic metalation strategies, and metal-free methods. Sequential arylations of heterocycles allow for the formation of multiaryl derivatives and are a preferred choice over de novo synthetic routes. This perspective sheds light on recent strategic advances to develop various sequential synthetic routes for the multiarylation of heteroarenes. This perspective addresses many challenges in optimizing sequential routes with respect to catalysts, reaction parameters, and various strategies adopted to obtain diversely arylated products.

Effective synthesis of benzimidazoles-imidazo[1,2-a]pyrazine conjugates: A comparative study of mono-and bis-benzimidazoles for antitumor activity

A novel series of 6-substituted-8-(1-cyclohexyl-1H-benzo[d]imidazole-6-yl)imidazo[1,2-a]pyrazine and 6-substituted-8-(1-benzyl-1H-benzo[d]imidazole-6-yl)imidazo[1,2-a]pyrazine is first time synthesized and screen in vitro biological activity for 60 human cancer cell lines representing nine different cancer types. Derivatives 10 and 36 show antitumor activity for all tested cell lines, display comparable full panel mean-graph midpoint growth inhibition (MG_MID GI₅₀) values of 2.10 and 2.23 μM, respectively. Furthermore, these derivatives show strong binding interactions with DNA and bovine serum albumin (BSA), studied through absorption, emission, and circular dichroism techniques. These spectroscopic studies reveal that imidazo[1,2-a]pyrazine-benzimidazoles 10 and 36, intercalate with ct-DNA as a leading interaction for fundamental biologically significant effects, with monobenzimidazole show better activity than bisbenzimidazole. These experiments have confirmed that the imidazo[1,2-a]pyrazine and benzimidazole moieties are efficient pharmacophores to trigger binding to DNA. These compounds have also interacted with bovine serum albumin protein that demonstrating high values of binding constant.

Investigation of rotameric conformations of substituted imidazo-[1,2-a]pyrazine: experimental and theoretical approaches

The different rotameric conformations of imidazo-[1,2-a]pyrazine have been synthesized and characterized by means of different experimental techniques, such as NMR, FTIR, and absorption spectroscopy and quantum chemical calculations. The different conformations were stabilized by hydrogen bonds, such as OH⋯N, ArH⋯N and ArH⋯ArH. The ground state optimizations and potential energy surface (PES) scanning profiles produced using density functional theory (DFT) show two stable rotameric forms for each molecule. The relative population of the conformations is affected by the strength of the hydrogen bonds. The calculated absorption spectra and isotopic shielding constants were acquired by time-dependent density functional theory (TD-DFT) and gauge invariant atomic orbitals (GIAO)-DFT, respectively. The strength of the hydrogen bonding interactions that resulted in the different conformations was studied by quantum theory of atoms in molecules (QTAIM).

The different rotameric conformations of imidazo-[1,2-a]pyrazine have been synthesized and characterized by means of different experimental techniques, such as NMR, FTIR, and absorption spectroscopy and quantum chemical calculations.

Synthesis of energy transfer cassettes via click and Suzuki–Miyaura cross coupling reactions

Novel cassettes capable of energy transfer involving simple synthetic methodsviz., click reaction at C-8 position and palladium catalyzed Suzuki–Miyaura cross coupling at C-6 position of imidazo[1,2-a]pyrazine, have been represented.

Synthesis, in vitro anticancer activity and SAR studies of arylated imidazo[1,2-a]pyrazine–coumarin hybrids

A diverse array of arylated imidazo[1,2-a]pyrazine–coumarin hybrids have been synthesized for in vitro anticancer activities.

Recent advances in development of imidazo[1,2-a]pyrazines: synthesis, reactivity and their biological applications

The synthesis, reactivity and multifarious biological activities at the different positions of imidazo[1,2-a]pyrazines are concisely discussed in this review.