G. Knor, Spontaneous nucleophilic addition of hydroxide ions to the meso-position of high-valent antimony-ore porphyrin complexes, J INORG BIO, 84(3-4), 2001, pp. 297-299
Bimolecular reactions of the antimony(V) porphyrin complexes SbO(tpp)OH, 1
and SbO(oep)OH. 2 with tetra-n-butylammonium hydroxide were investigated at
298 K in acetonitrile solution (tpp, dianion of 5,10,15,20-tetraphenylporp
hyrin and oep, dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin). Spontane
ous nucleophilic addition of hydroxide ions to the non-oxidized porphyrin m
acrocycle leads to novel hydroxyphlorin derivatives, which contain a satura
ted meso-carbon bridge. While this process is a reversible equilibrium reac
tion for the TPP derivative, the OEP complex undergoes subsequent demetalla
tion and oxidative ring cleavage in the presence of dioxygen. Possible impl
ications for the competitive inhibition of heme-oxygenase by high-valent me
talloporphyrin therapeutics are discussed. (C) 2001 Elsevier Science B.V. A
ll rights reserved.