Oxygenation of Phenanthriporphyrin and Copper(III) Phenanthriporphyrin: An Efficient Route to Phenanthribilinones

Abstract

Photooxidation of copper­(III) 5,6-dimethoxyphenathriporphyrin and copper­(III) 5,6-dioxophenanthriporphyrin, which contain phenanthrene or dioxophenathrene moieties built into the macrocyclic frameworks, resulted in the regioselective cleavage that afforded organometallic copper­(III) complexes of open-chain phenanthribilinone-type acyclic ligands terminated by carbonyl groups. The copper­(III) coordinates two carbon atoms of phenantherene (dioxophenanthrene) and two nitrogen atoms of pyrrole and pyrrolone units, preserving the donor sets of the paternal complexes. The primary dioxygen attack is located at the meso carbon atom adjacent to the phenanthrene moiety. Demetalation of copper­(III) 21-benzoyl-phenanthribilin-1-one and copper­(III) 21-benzoyl-dioxophenanthribilin-1-one yielded mainly two diastereomers [15Z , 20E ] and [15Z , 20Z ], which differ in the configurations at two Cα–C meso double bonds. The regioselectivity of the cleavage, detected in the course of experimental studies, has been substantiated by DFT investigations. The regioselective cleavage of 5,6-dimethoxyphenanthriporphyrin in reaction with basic iron­(III) acetate was detected, providing the synthetically efficient methodology to produce 21-benzoyl-dioxophenanthribilin-1-one.

Synthesis and Properties of Dibenzothiophene Embedded Heteroporphyrins

“…12−14 In recent times, the PAH embedded porphyrinoids have been receiving significant attention because of their unusual reactivity, different π-conjugation pathways, spectral properties, nature of aromaticity, and high tendency to form stable coordination and organometallic complexes in which metals may show uncommon oxidation states. 15−17 Some selected examples of PAH embedded porphyrinoids such as naphthalene 18−20 1, biphenyl 16 2, bypyridine 21 3, phenathrene 15,17,22 4, and phenanthroline 23 5 embedded porphyrinoids are shown in Chart 1. For example, the biphenyl embedded porphyrinoid 2 forms an organocopper complex in which the copper ion is stabilized in a +3 oxidation state.…”

Bis‐(Dibenzothiophene) Embedded Hexaphyrins: Synthesis, Structure and Properties

“…The PAH embedded porphyrinoids possesses structural features of both polycyclic aromatic hydrocarbons/heterocycles and cyclic polypyrrolic macrocycles. Recently, significant attention has been drawn towards synthesis of new polycyclic aromatic hydrocarbons/heterocycles because of the following reasons: (1) The PAH embedded macrocycles exhibit different π ‐conjugation pathways unlike polypyrrolic macrocycles such as porphyrinoids which show global conjugation; [33–35] (2) these macrocycles show variable degrees of aromaticity which varies from nonaromatic to antiaromatic [36–38] and (3) the PAH embedded porphyrinoids provide unique coordination environment to form coordination and organometallic complexes where metals may exhibit uncommon oxidation states and unusual reactivity [6,39–42] . Recently, we reported the synthesis of dibenzothiophene and dibenzofuran embedded porphyrins and showed that these macrocycles can act as ligands to form the Re(I) complexes readily [15] .…”

“…Polycyclic aromatic embedded porphyrinoids resulted from replacement of one or two pyrrole rings of porphyrinoids with polycyclic aromatic hydrocarbons/heterocycles (PAHs) [1][2][3] such as biphenyl [4] I, bipyridine [5] II, phenanthrene [6] III, naphthalene [7][8][9] IV, anthracene [10] V, dibenzofuran/ dibenzothiophene [11] VI, benzofuran/benzothiophene [12] VII and fluorene [13] VIII (Chart 1) have been receiving attention in recent years because of their unique structural and unusual physico-chemical properties. [14][15][16][17] In addition to the above mentioned macrocycles, several other PAHs such as (benzo) indene, [18][19][20] pyrene, [21,22] azulene [23][24][25][26] etc containing macrocycles have also been reported. These PAH embedded macrocycles are known to undergo organometallic reactivity like ring contractions, [25,26] oxygenations, [27,28] additional fragment substitutions [29] etc.…”

“…Recently, significant attention has been drawn towards synthesis of new polycyclic aromatic hydrocarbons/heterocycles because of the following reasons: (1) The PAH embedded macrocycles exhibit different π-conjugation pathways unlike polypyrrolic macrocycles such as porphyrinoids which show global conjugation; [33][34][35] (2) these macrocycles show variable degrees of aromaticity which varies from nonaromatic to antiaromatic [36][37][38] and (3) the PAH embedded porphyrinoids provide unique coordination environment to form coordination and organometallic complexes where metals may exhibit uncommon oxidation states and unusual reactivity. [6,[39][40][41][42] Recently, we reported the synthesis of dibenzothiophene and dibenzofuran embedded porphyrins and showed that these macrocycles can act as ligands to form the Re(I) complexes readily. [15] In this paper, we report the synthesis of first examples of dibenzothiophene embedded expanded porphyrins, bis-(dibenzothiophene) embedded hexaphyrins 1 & 2 and explored their structural and electronic properties using X-ray crystallography, 1D & 2D NMR, absorption, electrochemical and DFT, TD-DFT studies.…”

Synthesis and Aromaticity of Benzene‐Fused Doubly N‐Confused Porphyrins

“…The peripheral fusion of aromatic rings to porphyrinoid chromophores by using either higherp yrrole analogues as the starting pyrrole unit [6] or introducing suitable peripherals ubstituents such as ring-fusing moieties has been studied extensively. [7] Ring contractiono fh igherp orphyrinoids by core fusion is as trategy that has been used to produce new macrocyclicr ing systems. [8] These methodologies are quite effective for drastically modifying the electronic structures of the macrocyclic systems of porphyrinoids, so that they become panchromatic.…”