Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

Abstract

A comprehensive account of recent advances in the synthesis of imidazopyridines, assisted through transition-metal-catalyzed multicomponent reactions, C–H activation/functionalization and coupling reactions are highlighted in this review article. The basic illustration of this review comprises of schemes with concise account of explanatory text. The schemes depict the reaction conditions along with a quick look into the mechanism involved to render a deep understanding of the catalytic role. At some instances optimizations of certain features have been illustrated through tables, i.e., selectivity of catalyst, loading of the catalyst and percentage yield with different substrates. Each of the reported examples has been rigorously analyzed for reacting substrates, reaction conditions and transition metals used as the catalyst. This review will be helpful to the chemists in understanding the challenges associated with the reported methods as well as the future possibilities, both in the choice of substrates and catalysts. This review would be quite appealing to a wider range of organic chemists in academia and industrial R&D sectors working in the field of heterocyclic syntheses. In a nutshell, this review will be a guiding torch to envisage: (i) the role of various transition metals in the domain dedicated towards method development and (ii) for the modifications needed thereof in the R&D sector.

1,2‐Aminofunctionalization Reactions of Pyridino‐Alkynes via Carbophilic Activation

“…In this domain, considering the importance of synthesizing functionalized olefins, 1,2‐difunctionalization reaction of naturally abundant alkynes has been established as an important subset which enables the construction of stereodefined tri‐ and tetra‐substituted alkenes by syn ‐ or anti ‐selective introduction of two functional groups across the triple bond [1b,d,f,g,p,q] . Given the ubiquity of nitrogen‐containing molecules in nature serving as versatile building blocks for many pharmaceuticals, natural products, commodity chemicals and functional materials, 1,2‐aminofunctionalization reactions of alkynes have evolved as a thriving area of research [1f,g,l,q,2a,3a,b,4a] . Noteworthily, these aminofunctionalization reactions have been applied in achieving various annulation reactions for the synthesis of wide range of heterocyclic scaffolds highlighting the potential of these carbophilic activation strategies.…”

Towards Quantum Monte Carlo Forces on Heavier Ions: Scaling Properties

“…Most of the applications to date are limited to first and second row elements, although exciting prospects await in transition metal elements of third row and beyond. Transition metals have innumerable applications in materials research, because of their properties in, e.g., catalysis 28 and superconductivity 29 , and prevalence in semiconductors 30 and prospective 2D-materials 31,32 . Since transition-metal oxides are famous for their strong electronic correlation 33,34 and also often display sensitivity in optimized lattice structure to the description of correlation, the ability to quickly compute forces in beyond-density functional theory (DFT) methods like QMC is greatly needed for a fully consistent description of these materials.…”

“…− i (2 +1) v l (r iJ ) r iJ,γ r iJ α wαP (cos θ α iJ )Ψ T (...q α iJ ...) Ψ T (...r i ...)(28) − i (2 +1)v l (r iJ ) α   wα P (cos θ α iJ )T (...q α iJ ...) Ψ T (...r i ...)   (29) + i (2 +1)v l (r iJ ) α   wαP (cos θ α iJ )∂ i,µ Ψ T (...q α iJ ...) Ψ T (...r i ...) put braces under the terms that need to be computed beyond what's already computed for the nonlocal pseudopotential energy evaluation. In the last line, we have first what's essentially a Pulay term, and the last is a ZVZB like term.…”

Multiwalled carbon nanotubes crowned with nickel‐ferrite magnetic nanoparticles assisted heterogeneous catalytic strategy for the synthesis of benzo[d]imidazo[2,1‐b]thiazole scaffolds

“…[24] Also, despite the diversified advantages associated with carbon nanotubes, its use as a catalyst is hitherto unrivaled, although this can leads to the expedient synthesis of imidazo fused benzothiazole scaffolds. On keeping these observations in mind and continuation of our interest toward nanocatalysis, [25][26][27][28][29] we propose an alternative eco-friendly synthetic methodology for the synthesis of highly functionalized benzo[d]imidazo [1,2-b]thiazoles using multiwall carbon nanotubes mediated with nickelferrite magnetic nanoparticles (NiFe 2 O 4 -CNTs), as an efficacious, economical and noncorrosive heterogeneous catalyst, under aerobic conditions via. A 3 coupling followed by 5-exo-dig cyclization.…”