2.5.5 meso-Alkylidenyl-24-Hetero-22-Aza-m-Benziporphyrin
N
R 1
R 1
R 3
R 3
Synthetic routes yielding meso-alkylidenyl-24-thia-22-aza-m-benziporphyrin and
meso-alkylidenyl-24-oxa-22-aza-m-benziporphyrin have been reported by Lee and
coworkers [71]. Both of them were synthesized via the [3 + 1] strategy, starting from
the pyritripyrrane analogues 47 and appropriate dicarbinol 24 and using TFA as a
catalyst (Scheme 21). Oxapyriporphyrin 48-O was obtained with a 19% yield. 48-O
H
N
N
N
N
Ar 1
Ar 1
Ar 2
Ar 2
6
6-1-H
+
6-1'-H
+
6-2-H
+
H
N
N
N
N
H
Ar 1
Ar 1
Ar 2
Ar 2
H
N
N
N
N
H
Ar 1
Ar 1
Ar 2
Ar 2
N
NH
HN
N
Ar 1
Ar 1
Ar 2
Ar 2
H
+
Scheme 20 Monoprotonation of pyriporphyrin 6
HN
N
NH
X
NH
HN
N
H
Ar
Ar
48
EtO 2 C
EtO 2 C
EtO 2 C
CO 2 Et
EtO 2 C
EtO 2 C
CO 2 Et
CO 2 Et
1. TFA
2. DDQ
47
X
HO
HO
Ar
Ar
24
X
NH
HN
N
Ar
Ar
EtO 2 C
EtO 2 C
CO 2 Et
CO 2 Et
50
X
N
N
N
Ar
Ar
EtO 2 C
EtO 2 C
CO 2 Et
CO 2 Et
49
X = S or O
for X = S
X = O
X = S or O
TFA
+
TEA
Scheme 21 Synthesis of meso-alkylidenyl-dihydro-22-aza-24-hetero-m-benziporphyrin 48, its
endocyclic isomer 49, and 22-aza-24-hetero-m-benziporphyrin 50 [71]
196
K. Hurej and L. Latos-Grażyński