Selectivity is one of the most challenging tasks to attain for the evolution of an ideal chemical reaction and particularly the discrimination exhibited by a reagent in the presence of two different reactants or functional groups is extremely troublesome. Highly intelligent natural systems overcomes selectivity issues with biological catalysts, predominantly with porphyrins such as cytochromes, catalyzing the oxidation-reduction processes, transport of dioxygen, destruction of peroxide, electron transfer reactions etc. and all form of life depends on it. These biological catalysts smartly tailored on the way to specific substrate and exert high levels of stereo-, regio- and chemo-selectivity. Porphyrins are tetradentate, very stable pi-conjugated macrocyclic compounds that can accommodate almost all metals in their central cavity and offer a high architectural flexibility in structure, which facilitates the chemical and biological parameters over a very broad range. Natural systems functions rather in a different way over the laboratory systems when it comes to entail selectivity in chemical conversions. Mimicking the bio-inspired chemistry associated with natural porphyrin complexes using synthetic porphyrinoids provide the cost effective, reliable alternatives to the other catalytic options. These porphyrinoid complexes are now well documented and creating their space as catalyst for various important organic transformations such as selective direct activation of inactivated C-H bonds (hydroxylation, halogenations, cyanation etc), oxidations, reductions, C-C and C-N couplings, refining of chemicals etc. Although, some researchers have compiled the different aspects of porphyrinoids, however, their contribution in deciding the reaction selectivities is an interesting idea to describe. Herein, our aim is to resolve the structural components of porphyrinoids accountable for the generation of selectivities in a chemical reaction and to describe how these porphyrinoids are controlling the selectivities through mechanistic considerations. (C) 2021 Elsevier B.V. All rights reserved.
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