Corroles hydrogenation

Coproporphyrin I synthesis, 816 Coronands classification, 919 metal ion complexes, 928,938 Corphins, 855 Coninoids, 983 Corrins, 871-888 demetallation, 882 deuteration, 879 electrophilic reactions, 879 metallation, 882 NMR, 878 nucleophilicity, 886 nucleophilic reactions, 879 oxidation, 879 oxidative lactamization, 880 oxidative lactonization, 880 photochemistry, 887 reactions, 879 at metal, 885 rearrangements, 879 redox chemistry, 888 spectra, 877 synthesis, 878 Corroles, 871-888 demetallation, 874 deuteration, 872 hydrogenation, 872 metallation, 874 reactions, 872 at metal, 875 redox chemistry, 876 synthesis, 871 Corticotropin zinc complexes medical use, 966 Cotton effect anils, 717... 

Aviv and Gross developed an interesting insertion reaction of diazo compounds into a secondary amine-hydrogen bond in the presence of Fe-corrole complexes (Scheme 7.8) [12], Competition experiments performed in the presence of an amine and an alkene revealed the N—H-insertion reaction to be much faster than the cyclopropanation of the C=C bond. Apart from this chemoselectivity issue, the reactions are characterized by their very short reaction times most insertion reactions were completed within 1 min at room temperature. Most recently, Woo s group reported on a similar process using commercially available iron tetraphenyl-porphyrin [Fe(TPP)] dichloride [13]. 

Corrole (Fig. 2) is an aromatic tetradentate N4 ligand in which three of four nitrogen atoms are linked to hydrogens that can be easily substituted. It readily forms stable anions which are also aromatic as demonstrated by their electronic spectra showing an intense absorption in the high energy region [8] (Fig. 8). 

It is interesting to note that in the structure of both rhodium and cobalt complexes the corrole framework shows a higher degree of planarity than that observed in the free ligand where a large distortion is induced by contacts between the inner hydrogen atoms [11]. The free base corrole macrocycle in its unprotonated form seems to be very flexible and the macrocycle core can expand to accommodate a large metal ion such as Rh3+ in a [Pg.89]

FIGURE 3.19 High-valent corrole and corrolazine complexes. Oxygen and hydrogen atom transfer reactions of oxomanganese(V) corrole/corrolazine complexes. 

Recently, Kadish et al. synthesized three series of Co corroles (shown in Figure 4.11(D)) and investigated their catalytic activity toward the O2 reduction reaction.The mixed valent Co(II)/ Co(III) complexes, (PCY)Co2, and the biscorrole complexes, (BCY)Co2, both contain two Co(III) ions in their air-stable forms. It was foimd that all these complexes could catalyze the direct four-electron pathway for O2 reduction to H2O in aqueous acidic electrolyte. The most efficient catalysis process was observed when the complex had an anthracene spacer. The four-electron transfer pathway was further confirmed by RRDE measurement, in which only a relatively small amount of hydrogen peroxide was detected at the ring electrode in the vicinity of E1/2 0.47 V vs SCE for (PCA)Co2 and 0.39 V for (BCA)Co2. The cobalt(III) mono-corrole, (Me4Ph5Cor)Co, could also catalyze ORR at En2 = 0.38 V, with the final products being an approximate 50% mixture of H2O2 and H2O. 

Doubly BCOD-fused corrole 86 was prepared by the [2 + 2] method via ac-biladiene hydrogen-bromide complex 85 using tetraethyl dipyrromethane 85 [84] and BCOD-fused pyrrolecarbaldehyde 17a in the presence of hydrobromic acid (Scheme 15.18 K. Kuroki, N. Ono, and H. Uno, unpublished result). The retro-Diels-Alder reaction of 86 at 200 °C for 1 h would give dibenzocorrole 87, which was turned out to be labile under air. The product obtained was a mixture probably derived from oxygenated compounds such as oxaporphyrin... 

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