1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

2 State of The Art & Aims
They were developed by N. JUX and co-workers and proved excellently suited for the
construction of several tailored systems with diverse applications. For example, highly
charged porphyrins and their metal complexes were synthesized 70 for the investigation of
fundamental biochemical subjects like the binding of NO to heme proteins under
physiological conditions 71 or the modeling of cytochrome P450NOR 72 . Porphyrin crown ether
conjugates were investigated as ditopic receptors 73 and metal complexes of inherently chiral
cycloamino-porphyrin systems M-29 were accessed 74 for potential application in
enantioselective catalysis.
The latter, an example of whom is depicted in Scheme 18, were recently synthesized by
pyrolysis of o-(azidomethyl) porphyrins. Those reactions, affording harsh conditions, turned
out to be unreliable and limited to metalloporphyrins. Due to the only moderate stability of
the obtained exocyclic amino-porphyrins, free base systems were inaccessible and trials in
order to functionalize the amine moiety in M-29 remained unsuccessful. 74,75 Nevertheless,
the concept worked and is worth to be further investigated albeit under modifications.
22
HN
N
N
M
N
M-29
N
Scheme 18. General structure for cycloamino-porphyrin
systems M-29 where M = Cu II , Ni II or Mn V . The compounds
should be present in racemic mixtures due to atropisomerism.
To tackle those problems, the architecture could be altered from amine-based to ketone-
based exocycles (Scheme 19) analog to compounds recently reported by CALLOT et al. 76 For
that purpose, the synthetic pathway has to be completely altered.
Scheme 19. General structure for cycloketo-porphyrin
systems M-53 where M = Cu II , Ni II or 2H. Also here,
atropisomers should be formed to give a racemic mixture.
O
N
N
M
N
M-53
N