1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

3 Discussion and Results
The remainder characterization data being summed up in the experimental section
appeared well comparable to the ones for other porphyrin building blocks of that kind and
will hence not be further discussed here.
For the annulation, also 79 was initially transformed into its corresponding copper(II)
complex by reaction via standard conditions in acidified CH2Cl2. 96,97 The conversion into the
tetra-ethanoic acid chloride turned out to be difficult as Cu(II)-79 could not be solubilized in
the usual CH2Cl2 / oxalyl chloride mixture. The conversion was finally conducted in pure
oxalyl chloride, C2O2Cl2, at room temperature over a period of 6 h. After complete
evaporation of the reagent being also the solvent, the activated derivative of Cu(II)-79 could
be taken up in CH2Cl2 and reacted with the tin tetrachloride catalyst, SnCl4. Thereby the color
did not change to green as it was observed in all other cycloketo-porphyrin syntheses but
the brownish solution brightened up to get a salmon-like color. TLC monitoring indicated the
formation of two species as it was expected (see Scheme 49).
HO 2 C
108
CO 2 H
N
N
Cu
N
N
HO 2 C
CO 2 H
O
O
N
NH HN
N
O
O
+
O
O
N
NH HN
N
Cu(II)-79 80 81
Scheme 49. Synthesis of tetra-annulated cycloketo-porphyrins 80 and 81 from Cu(II)-79.
Applied conditions: 1. C2O2Cl2, rt, 6h; 2. SnCl4, CH2Cl2, rt, 20 min; 3. TFA, H2SO4, rt, 1h.
After work-up, the crude product mixture was complete evaporated to subject it to the
demetallation procedure already described 96 , but the material could not be solubilized
under these conditions. Thus, the reaction was repeated, the obtained product mixture
concentrated and demetallated as it is known that the free-base system exhibit a higher
solubility. But also then, it was not possible to obtain soluble products.
So it has to be concluded that multiple annulation to poly-exocyclic compounds seems
possible but does not deliver soluble compounds to be purified and characterized. Hence,
the study of other poly-annulated compounds was set aside and it was further focused on
the implementation of an additional functional group to mono-annulated systems.
O
O