Attempts of the Synthesis of Highly Functionalized Porphyrins at the β-Positions: Nitration of Exhaustively Substituted Moieties in the ’Eastern Half ’ and Mass-Spectral Study of the Reaction Products

Ostrysz, Sylwia; Mikus, Agnieszka; Ostrowski, Stanisław

doi:10.6060/mhc170405o

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“…Their treatment with 33% nitric acid for ca 5 h (CHCl 3 , at r.t., under argon) resulted in the formation of a mixture of many polynitro‐substituted products, even exhaustively derivatized at the β ‐positions ( e. g . 88 ), however they were isolated from complex mixtures with low yields [86] …”

Section: Nitration Of Porphyrin Derivatives At the β‐Positionsmentioning

confidence: 99%

Nitration of Porphyrin Systems: A Toolbox of Synthetic Methods

Mikus

Łopuszyńska

2020

Chemistry An Asian Journal

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This review addresses nitration reactions of porphyrin derivatives. Simple porphyrins modifications afford valuable intermediates in this area of chemistry. They are useful materials for further transformations, as the NO2 group introduced into parent porphyrin system increases its electrophilic character, thus allowing a broad spectrum of subsequent reactions, e. g. reduction of NO2 to NH2, subsequent diazotisation, nucleophilic substitution of hydrogen (in ortho‐position to NO2), a variety of cyclizations, etc. Such reactions are often utilized in the first steps of the designed syntheses, leading to attractive and useful target porphyrin molecules. This approach (via nitro‐derivatives) allows synthesizing numerous porphyrin‐like compounds of a high degree of complexity, and has thus become one of the methods choice. The substitution by NO2 group can take place at all positions of the porphyrin systems: four meso‐positions (5, 10, 15, 20) and eight positions β (2, 3, 7, 8, 12, 13, 17, 18). The third possibility includes the nitration in meso‐aryl rings attached to positions 5, 10, 15, and 20. The latter derivatives (meso‐aryl substituted ones) are a large, well‐known group of synthetic porphyrins. The nitration reactions described herein follow three various mechanisms: (a) radical, (b) via π‐cation radicals and π‐dications, and (c) electrophilic. All the above cases are discussed in detail. According to our knowledge, this is the first such systematic account concerning these reactions.

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Section: Nitration Of Porphyrin Derivatives At the β‐Positionsmentioning

confidence: 99%