Both-faces hindered porphyrins. Part 1. Synthesis and characterization of basket-handle porphyrins and their iron complexes

Abstract
The synthesis of the ‘both-faces’ hindered porphyrins using two different methods is reported. These so-called ‘basket-handle’ porphyrins (BHP) are derived from 5,10,15,20-tetraphenylporphyrin in which two opposite phenyl groups are bridged by alkylene or arylene-p-bisalkylene chains. In addition to the desired compounds [the cross-trans-linked isomer (7)], two other isomers were obtained [adjacent-trans-linked (8) and adjacent-cis-linked (9)]. These were separated by t.l.c. on silica gel and then individually characterized. The structural assignment of the three isomers in the five series studied was based on the 1H n.m.r. spectra of the free bases and of their iron(II) complexes.