Porphyrins as 1,3-dipoles in 1,3-dipolar cycloadditions

Similar protocols have been followed for the synthesis of other porphyrin-C6o diads where the linkage between Cm and porphyrin moieties occurs through the ortho, meta or para positions of the phenyl ring of the porphyrin macrocycle 00PP598, 03JPC(A)8834 and 06SC2135 . 

In terms of synthetic methodologies for the preparation of porphyrinic azomethine ylides, the porphyrin moiety, in the examples above, was the carbonyl component. However, there are also examples where the porphyrin is used as the a-amino acid component. 

Our first entry to the use of porphyrins as dipolarophiles in 1,3-DC reactions involved the reaction of porphyrins with azomethinic ylides, generated in situ from a-amino acids and aldehydes, to yield chlorins and isobacteriochlorins (bisadducts) 99CC1767, 05JOC2306 . 

This strategy has been successfully applied to other porphyrins, however the best yields were obtained with porphyrins having electron-withdrawing groups at the meso positions of the macrocycle 05JOC2306, 04JBCS923 . 

Finally, the condensation of the tripyrrane 65 with the diformyl pyrrole 66, in a TFA/CHCI3 solution, gave porphyrins 67. Such porphyrins were then used in 1,3-DC 

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