Corrole meso phenyl

Four different synthetic procedures have been examined for the preparation of the triphenyl derivative, the fourth one suggested by the synthetic conditions developed to obtain the diphenyl derivatives. In the first three procedures it has been impossible to isolate the triphenyl-dihydrobilin. Its formation has been demonstrated, however, by monitoring the electronic spectrum of the reaction mixture and the cyclization to corrole has been carried out in situ. The synthesis that gave the highest yield (20%) and that avoids tedious purification procedures is outlined in Fig. 10. It involved the acidic condensation of benzaldehyde with two equivalents of 3,3, 4,4 -tetramethyl-meso-phenyl-dipyrromethane-5,5 ... 

The synthesis of cobalt meso-diphenyl corrolates has also been reported [31]. The synthetic procedure involves the acidic condensation of 3,4-dimethyl-2-(a-hydroxybenzyl)pyrrole-5-carboxylic acid with 3,3, 4,4 -tetramethyl dipyrro-methane, followed by reaction with cobalt salts. The reaction afforded a mixture of two isomers Co(5,15-OMDPC)PPh3 and Co(5,10-OMDPC)PPh3. The formation of this latter isomer has been explained by the high tendency of self condensation of the starting pyrrole under the reaction conditions, 2-(a-hydroxybenzyl)meso-phenyl dipyrromethane can be formed. This species would afford the Co(5,10-OMDPC)PPh3 by further condensation with the dipyrromethane unit present in excess in the reaction mixture. 

Data relative to the 400 MHz H-NMR spectra of cobalt corrolates are reported in Table 16. The strong shift due to the macrocycle ring current demonstrates that the presence of the meso-phenyl substituents does not cause the loss of aromaticity. The meso-protons of the monophenyl derivative resonate at the same chemical shift value observed for the meso-unsubstituted complex. 

The synthesis of bis-(meso-phenyl)cobalt(III) corroles 2.150 and 2.151 was achieved by Licoccia and coworkers in 1994. The procedure used involved first carrying out an acid-catalyzed condensation between the diacid dipyrrylmethane 2.35 and the a-hydroxybenzyl pyrrole 2.147. This afforded a mixture of two dideox-ybiladienes-ac (i.e., 2.148 and 2.149), which were not isolated. Rather, as the next and final step in the synthesis, these were treated directly with Co(OAc)2 in the presence of PPh3. This yielded a 1 2 ratio of the two cobalt(III) corrole products 2.150 and 2.151 (total yield 20%) (Scheme 2.1.39). 

Two papers have been published to date on meso-substituted derivatives of corrole [30, 31]. Four new cobalt complexes have been prepared and characterized [triphenylphosphine(2,3,7,8,12,13,17,18-octamethyl-1O-phenyl-corrolato)-cobalt (III)] (Co(OMMPC)PPh3), [triphenylphosphine (2,3,7,8,12,13,17,18-octamethyl-5,10,15-triphenylcorrolato)cobalt (III)] (Co(OMTPC)PPh3), [tri-phenylphosphine(2,3,7,8,12,13,17,18-octamethyl-5,10-diphenylcorrolato)cobalt (III)] (Co(5,10-OMDPC)PPh3) and [triphenylphosphine (2,3,7,8,12,13,17,18-octamethyl-5,15-diphenylcorrolato)cobalt(III)] (Co(5,15-OMDPC)PPh3). 

A general feature of weso-phenyl substituted Co3 + corrolates is then that the planarity of the macrocyclic ligand is maintained in solution the pattern shown by the resonances due to the peripheral methyl groups in fact are indicative of the existence of a C2 symmetry axis the direct pyrrole-pyrrole bond typical of a planar corrole skeleton, confirmed also by the signals due to the meso-protons, if present. 

Tetrakis(phenyl) porphyrin 2- (Bis (salicylideneamino) methyl) phenol meso-T ris (phenyl)corrole... 

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