Synthesis and characterization of partially β-fluorinated 5,10,15,20-tetraphenylporphyrins and some derivatives

The synthesis of partially beta-fluorinated meso-tetraphenylporphyrins using Lindsey conditions, has been examined, starting either from 3,4-difluoro-1H-pyrrole or from 3-fluoro-1H-pyrrole. In the case of the first synthon, condensation with pyrrole and benzaldehyde afforded a mixture of porphyrins of general formula beta-FnTPP (n=0,2,4,6,8) displaying linearly correlated spectroscopic and electrochemical properties. With the second synthon, condensation with benzaldehyde produced an unresolvable mixture of beta-tetrafluoroporphyrins presenting spectroscopic and electrochemical properties in coherence with those observed in the first case. Preliminarily, the synthesis and isolation of the hitherto unknown 3-fluoro-1H-pyrrole has been approached via several methods. (C) 2002 Elsevier Science Ltd. All rights reserved.