Synthesis of Hydrocarbon-strapped Porphyrins Containing Quinone and Phenolic Groups
Morgan, B. and David Dolphin
J. Org. Chem.
A general synthesis is described for strapped porphyrins, e.g., I (n = 5, 6) in which a functional group is held above the porphyrin core by a hydrocarbon chain attached to diagonally opposite corners of the porphyrin ring. In this strategy, all the units necessary for the porphyrin macrocycle were assembled at each end of the bridging strap and the porphyrin ring forming reaction postponed until the final stages of the synthesis. The key step in the synthesis was a double Wittig reaction of α-free phosphonium salt II with 4,2,5-Me(OHC)2C6H2OMe to give bis-pyrrole III. The NMR and optical spectra of the strapped porphyrins are discussed.