1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

3 Discussion and Results
116
HO 2 C
O
N
N
NH HN
N
N
Cu
N
N
NO 2
NO 2
a.
O
N
N
Cu
N
N
b.
NO 2
a.
O
N
N
Cu
N
N
b.
NH 2
O
N
NH HN
N
90 Cu(II)-91 91
Scheme 55. Ring closing procedure applied to 90 to finally yield 91 via its copper(II) complex
Cu(II)-91. Applied conditions: a.: 1. Cu(OAc)2·2 H2O, CH2Cl2/MeOH/AcOH, rt, 15 h; 2. C2O2Cl2,
CH2Cl2, rt, 1.5 h; 3. SnCl4 , CH2Cl2, rt, 10 min; b. TFA/H2SO4, rt, 45 min.
O
N
NH HN
N
Cu(II)-91 Cu(II)-92 92
Scheme 56. Reduction protocol leading to free base 15 4 -amino substituted cycloketoporphyrin
92 via its corresponding copper(II) complex. Applied conditions: a.: SnCl2 in
EtOH/EtOAc/HCl, reflux, 3-5 h; 138 b.: TFA/H2SO4, rt, 45 min.
While the abovementioned protocol gave rise to free base 15 4 -amino substituted system 92
in 81.8 % isolated yield without any further reduction of the exocyclic ketone, it was not
possible to directly apply that reduction procedure to the free base nitro derivative as that
led to the formation of the corresponding tin(IV) complex Sn(IV)-92. Also the reaction time
and acidity of the reaction media in reducing Cu(II)-91 had to be carefully stuck to since else
transmetallation occurred also leading to undesirable tin(IV) complex formation.
All those compounds were fully characterized and investigated concerning their
photophysical parameters what will be treated in the following paragraphs.
NO 2
NH 2