105342-50-5Relevant articles and documents
Rections of Porphyrins with Nitronium Tetrafluoroborate in Pyridine
Cavaleiro, Jose A. S.,Neves, Maria G. P. M. S.,Hewlins, Michael J. E.,Jackson, Anthony H.
, p. 575 - 580 (2007/10/02)
Octaethylporphyrin reacts with nitronium tetrafluoroborate in pyridine at 80 deg C to afford the meso-nitroporphyrin in 31percent yield after 6 h, whereas the zinc complex reacts very rapidly at 20 deg C to afford 63percent of the meso-nitroporphyrin after work-up. meso-Tetraphenylporphyrin, however, only reacted slowly with nitronium tetrafluoroborate in pyridine at rather higher temperatures in a sealed tube to afford the β-pyridinium salt of the porphyrin as the major product; again when the zinc complex of tetraphenylporphyrin was used the β-pyridinium salt was formed in 85percent yield in a few minutes at 20 deg C.Brief treatment of the tetraphenylporphyrin pyridinium salt with alkali afforded a ring-opened glutaconaldehyde derivative of the β-aminoporphyrin, analogous to the well-known Zincke's compounds which can be obtained from N-arylpyridines with alkali.The structures of both the ring-opened products from the pyridinium porphyrin and from N-(2,4-dinitrophenyl)pyridinium chloride, were assigned by highfield n.m.r. spectroscopy, including decoupling and n.O.e. difference measurements.
