2.5.3 22-Aza-m-Benziporphyrin (Pyriporphyrin)
N
R
R
R
R
R
R
In the very first attempt to obtain β-alkylated pyriporphyrin (22-aza-mbenziporphyrin) 42, carried out by Berlin and Breitmaier in 1994, pyridine-2,6dicarbaldehyde 39 reacted with tripyrrane 40 efficiently providing β-alkylated
3-aza-dihydro-m-benziporphyrin (dihydropyriporphyrin, pyriporphyrinogen) 41
[70]. The subsequent intensive oxidation of 41 with p-chloranil in excess did not
result in the formation of the pursued β-alkylated 22-aza-m-benziporphyrin 42.
Instead of 42, nonaromatic pyriporphyrinone 43 was formed as the single
isolable macrocyclic product [70]. In contrast, the gentle oxidation of 41 resulted
in the oxidative coupling of 41, generating the dimeric structure 44, in which
two macrocyclic subunits are bridged by the C(sp
3 ) meso –C(sp
3 ) meso single bond
(Scheme 18).
2.5.4 meso-Tetraaryl-22-Aza-m-Benziporphyrin
N
R
R
R
R
N
OHC
CHO
NH HN
HN
HOOC
HOOC
37
N
NH
HN
+
35
N
36
TFA
38
N
NH
HN
N
PhOCOCl
PhO
O
Scheme 17 Synthesis of 3-aza-dihydro-m-benziporphyrin
194
K. Hurej and L. Latos-Grażyński
N
R
R
R
R
R
R
In the very first attempt to obtain β-alkylated pyriporphyrin (22-aza-mbenziporphyrin) 42, carried out by Berlin and Breitmaier in 1994, pyridine-2,6dicarbaldehyde 39 reacted with tripyrrane 40 efficiently providing β-alkylated
3-aza-dihydro-m-benziporphyrin (dihydropyriporphyrin, pyriporphyrinogen) 41
[70]. The subsequent intensive oxidation of 41 with p-chloranil in excess did not
result in the formation of the pursued β-alkylated 22-aza-m-benziporphyrin 42.
Instead of 42, nonaromatic pyriporphyrinone 43 was formed as the single
isolable macrocyclic product [70]. In contrast, the gentle oxidation of 41 resulted
in the oxidative coupling of 41, generating the dimeric structure 44, in which
two macrocyclic subunits are bridged by the C(sp
3 ) meso –C(sp
3 ) meso single bond
(Scheme 18).
2.5.4 meso-Tetraaryl-22-Aza-m-Benziporphyrin
N
R
R
R
R
N
OHC
CHO
NH HN
HN
HOOC
HOOC
37
N
NH
HN
+
35
N
36
TFA
38
N
NH
HN
N
PhOCOCl
PhO
O
Scheme 17 Synthesis of 3-aza-dihydro-m-benziporphyrin
194
K. Hurej and L. Latos-Grażyński